MCP Mailtrap Server

Official Mailtrap MCP Server

The official MCP server for Mailtrap — the email delivery platform. It connects your Mailtrap account to Claude, Cursor, VS Code, and other MCP-compatible AI assistants.

Send transactional and bulk email, test messages safely in Email Sandbox, manage templates, contacts, sending domains, and webhooks, inspect email logs and delivery statistics, troubleshoot deliverability, and manage account resources — all using natural-language prompts.

Capabilities

• Email API and SMTP — Send transactional and bulk email, including batch and template-based messages.
• Email testing — Test messages in Email Sandbox and inspect content, headers, attachments, spam scores, and HTML client compatibility.
• Delivery monitoring — Search email logs, inspect event history, and analyze delivery, bounce, open, click, and spam rates.
• Email infrastructure — Manage sending domains, DNS verification, webhooks, and suppressions.
• Contacts — Manage contacts, lists, custom fields, and events, with imports and exports.
• Account management — Review billing usage and manage access, permissions, API tokens, and sub-accounts.

Supported MCP Clients

Works with Claude Desktop, Claude Code, Cursor, VS Code, and any other MCP-compatible client. Setup instructions for each are below.

Prerequisites

Before using this MCP server, you need to:

1. Create a Mailtrap account
2. Verify your domain
3. Get your API token from Mailtrap API settings
4. Get your Account ID from Mailtrap account management

Required Environment Variables:

• MAILTRAP_API_TOKEN - Required for all functionality
• MAILTRAP_ACCOUNT_ID - Required for templates, stats, email logs, sandbox list/show, sending domains, and suppressions. Optional only for the send tools (send-email, send-sandbox-email, and the batch-send-* tools), the email campaign tools, the company info tools, and the tracking opt-out tools.

Optional (can be passed as tool parameters instead):

• DEFAULT_FROM_EMAIL - Default sender email when from is not provided to send-email, send-sandbox-email, or the batch-send-* tools (where it fills base.from). Enables switching sender per call via the from parameter.
• MAILTRAP_SANDBOX_ID - Default sandbox (test inbox) ID when a tool's sandbox_id is not provided (legacy test_inbox_id on send/list/show sandbox message tools still accepted). Enables switching inboxes per call via parameters.
• MAILTRAP_TEST_INBOX_ID - Legacy alias for MAILTRAP_SANDBOX_ID; still read as a fallback for existing configs.
• MAILTRAP_ORGANIZATION_ID - Required for organization tools (list-sub-accounts, create-sub-account).
• MAILTRAP_ORGANIZATION_API_TOKEN - Organization-scoped API token. Required for organization tools (separate from MAILTRAP_API_TOKEN).

Quick Install

Docker

Run the server over stdio with the Docker MCP Catalog image:

docker run --rm -i \
  -e MAILTRAP_API_TOKEN="${MAILTRAP_API_TOKEN}" \
  -e MAILTRAP_ACCOUNT_ID="${MAILTRAP_ACCOUNT_ID}" \
  -e DEFAULT_FROM_EMAIL="${DEFAULT_FROM_EMAIL}" \
  -e MAILTRAP_SANDBOX_ID="${MAILTRAP_SANDBOX_ID}" \
  -e MAILTRAP_ORGANIZATION_ID="${MAILTRAP_ORGANIZATION_ID}" \
  -e MAILTRAP_ORGANIZATION_API_TOKEN="${MAILTRAP_ORGANIZATION_API_TOKEN}" \
  mcp/mailtrap

See Prerequisites for required and optional environment variables.

To build from this repository: docker build -t mcp/mailtrap .

Smithery CLI

Smithery is a registry and installer for MCP servers that works with AI clients.

Install the published server (mailtrap/mailtrap-mcp) into a local client (replace the client name as needed):

npx -y smithery mcp add mailtrap/mailtrap-mcp --client claude

See the Smithery CLI docs for other clients (cursor, windsurf, etc.) and for publishing updates.

Setup

Claude Desktop

Use MCPB to install the Mailtrap server. You can find those files in Releases.
Download .MCPB file and open it. If you have Claude Desktop - it will open it and suggest to configure.

Claude Desktop or Cursor

Add the following configuration:

{
  "mcpServers": {
    "mailtrap": {
      "command": "npx",
      "args": ["-y", "mcp-mailtrap"],
      "env": {
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "[email protected]",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
      }
    }
  }
}

If you are using asdf for managing Node.js you must use absolute path to executable (example for Mac)

{
  "mcpServers": {
    "mailtrap": {
      "command": "/Users/<username>/.asdf/shims/npx",
      "args": ["-y", "mcp-mailtrap"],
      "env": {
        "PATH": "/Users/<username>/.asdf/shims:/usr/bin:/bin",
        "ASDF_DIR": "/opt/homebrew/opt/asdf/libexec",
        "ASDF_DATA_DIR": "/Users/<username>/.asdf",
        "ASDF_NODEJS_VERSION": "20.6.1",
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "[email protected]",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
      }
    }
  }
}

Claude Desktop config file location

Mac: ~/Library/Application Support/Claude/claude_desktop_config.json

Windows: %APPDATA%\Claude\claude_desktop_config.json

Cursor config file location

Mac: ~/.cursor/mcp.json

Windows: %USERPROFILE%\.cursor\mcp.json

VS Code

Manually changing config

Run in Command Palette: Preferences: Open User Settings (JSON)

Then, in the settings file, add the following configuration:

{
  "mcp": {
    "servers": {
      "mailtrap": {
        "command": "npx",
        "args": ["-y", "mcp-mailtrap"],
        "env": {
          "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
          "DEFAULT_FROM_EMAIL": "[email protected]",
          "MAILTRAP_ACCOUNT_ID": "your_account_id",
          "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
        }
      }
    }
  }
}

[!TIP] Don't forget to restart your MCP server after changing the "env" section.

MCP Bundle (MCPB)

For easy installation in hosts that support MCP Bundles, you can distribute an .mcpb bundle file.

# Build TypeScript and pack the MCPB bundle
npm run mcpb:pack

# Inspect bundle metadata
npm run mcpb:info

# Sign the bundle for distribution (optional)
npm run mcpb:sign

This creates mailtrap-mcp.mcpb using the repository manifest.json and built artifacts in dist/.

Usage

Once configured, you can ask agent to send emails and manage templates, for example:

Email Sending Operations:

• "Send an email to [email protected] with the subject 'Meeting Tomorrow' and a friendly reminder about our upcoming meeting."
• "Email [email protected] about the project update, and CC the team at [email protected]"
• "Send the welcome template (uuid b81aabcd-1a1e-41cf-91b6-eca0254b3d96) to [email protected] with variables { name: 'Alex' }"
• "Send a sandbox email to [email protected] with subject 'Test Template' to preview how our welcome email looks"

Email Logs (debug delivery):

• "List my recent sent email logs"
• "Show email logs for emails sent to [email protected]"
• "Get the email log message for ID abc-123-uuid to check delivery status"

Sending Statistics:

• "Get sending stats for January 2025"
• "Show delivery rates broken down by domain for last month"
• "What are my email stats by category from 2025-01-01 to 2025-01-31?"

Sandbox Operations:

• "Get all messages from my sandbox inbox"
• "Show me the first page of sandbox messages"
• "Search for messages containing 'test' in my sandbox inbox"
• "Show me the details of sandbox message with ID 5159037506"

Template Operations:

• "List all email templates in my Mailtrap account"
• "Create a new email template called 'Welcome Email' with subject 'Welcome to our platform!'"
• "Update the template with ID 12345 to change the subject to 'Updated Welcome Message'"
• "Delete the template with ID 67890"

Sending Domains:

• "List my sending domains"
• "Get sending domain with ID 3938"
• "Create a sending domain for example.com"
• "Turn on click tracking for sending domain 3938"
• "Delete sending domain 3938"
• "Get sending domain 3938 with DNS setup instructions"
• "Show the company info for sending domain 3938"
• "Set the company info for domain 3938 to Acme Inc, 123 Main St, San Francisco, US, 94105, https://acme.com"
• "Change the company info city for domain 3938 to New York"

Suppressions:

• "List suppressions for [email protected]"
• "Suppress [email protected] on the transactional stream of domain 3938"
• "Show me all suppressed email addresses"
• "Why is [email protected] not receiving my emails?"
• "Remove [email protected] from the suppression list"

Tracking Opt-outs:

• "Stop tracking opens and clicks for [email protected] on domain 3938"
• "List everyone who opted out of tracking"

Contacts and Lists:

• "Add [email protected] to my newsletter contact list"
• "Show me all my contact lists"
• "Create a contact field called 'signup_source' for tracking where contacts came from"
• "Update the contact [email protected] to set their plan to 'pro'"
• "Import contacts from this CSV into my onboarding list"
• "Export all contacts from my newsletter list"
• "Record a 'trial_started' event for contact [email protected]"

Webhooks:

• "List all webhooks configured on my account"
• "Create a webhook pointing to https://example.com/hooks/mailtrap for bounce and spam events"
• "Update webhook 4821 to also send delivery events"
• "Delete webhook 4821"

Account and Billing:

• "What's my current billing usage this month?"
• "How many emails do I have left in my plan?"
• "List everyone who has access to this Mailtrap account"
• "Show me the permission resources available on my account"

API Tokens:

• "List all API tokens on my account"
• "Create a new API token for the staging environment"
• "Reset the API token with ID 1234"
• "Delete the unused API token 1234"

Organization and Sub-Accounts:

• "List all sub-accounts in my organization"
• "Create a new sub-account for the client project 'Acme Corp'"

Available Tools

send-email

Sends a transactional email through Mailtrap. Supports two mutually exclusive modes — inline content (subject + text/html) or template-based (template_uuid).

Parameters:

• from (optional): Sender as { email, name? } (a bare email string is also accepted at runtime). If not provided, DEFAULT_FROM_EMAIL is used.
• to (optional): Array of recipients as { email, name? } objects (bare email strings, or a single non-array address, are also accepted at runtime). Optional if cc or bcc is provided; at least one of to / cc / bcc must contain a recipient.
• cc (optional): Array of CC recipients as { email, name? } objects (bare email strings also accepted at runtime).
• bcc (optional): Array of BCC recipients as { email, name? } objects (bare email strings also accepted at runtime).
• subject (conditional): Email subject line. Required for inline sends; must be omitted when template_uuid is set.
• text (conditional): Email body text. Required (alongside or instead of html) for inline sends; must be omitted when template_uuid is set.
• html (conditional): HTML version of the email body. Required (alongside or instead of text) for inline sends; must be omitted when template_uuid is set.
• category (optional): Email category for tracking and analytics. Must be omitted when template_uuid is set.
• template_uuid (optional): Use a Mailtrap email template instead of inline content. When set, subject / text / html / category must be omitted (per Mailtrap API).
• template_variables (optional): Object of variables substituted into the template referenced by template_uuid. Only allowed together with template_uuid.

batch-send-transactional-email

Sends a batch of transactional emails in one Mailtrap API call (default sending stream). Shared fields go on base; per-recipient overrides go in requests[]. Each request must include at least one recipient via to, cc, or bcc. Same inline-vs-template mutual exclusion as send-email — checked after merging base with each request.

Parameters:

• base (optional): Object with fields shared across the batch.
  • from (optional): Sender as { email, name? } (a bare email string is also accepted at runtime). Falls back to DEFAULT_FROM_EMAIL.
  • reply_to (optional): Reply-to address.
  • subject / text / html / category (optional, inline mode): Default content for every request.
  • template_uuid / template_variables (optional, template mode): Default template + variables. Mutually exclusive with the inline fields.
  • custom_variables (optional): Default custom variables (string-valued).
  • headers (optional): Default custom headers.
• requests (required): Non-empty array of per-recipient messages. Each entry has:
  • to (optional): Array of recipients as { email, name? } objects (bare email strings, or a single non-array address, are also accepted at runtime). Optional if cc or bcc is provided; at least one of to / cc / bcc must contain a recipient.
  • cc, bcc, reply_to (optional).
  • Inline (subject/text/html/category) or template (template_uuid/template_variables) overrides; any field omitted falls back to the matching base value.
  • custom_variables, headers (optional).

batch-send-bulk-email

Sends a batch of bulk emails through Mailtrap's bulk-stream API. Same base + requests[] shape, validation, and inline-vs-template rules as batch-send-transactional-email — the only difference is that this tool routes the call through the bulk endpoint instead of the transactional one. See the parameters above.

list-email-logs

Lists sent email logs (delivery history) with optional pagination and filters. Use to debug delivery issues from the IDE.

Parameters:

• search_after (optional): Pagination cursor from the previous response's next_page_cursor
• sent_after (optional): ISO 8601 date/time; only logs sent after this time
• sent_before (optional): ISO 8601 date/time; only logs sent before this time
• from_email (optional): Filter by sender email; use with from_operator (default: ci_equal)
• to_email (optional): Filter by recipient email; use with to_operator (default: ci_equal)
• status (optional): Filter by delivery status: delivered, not_delivered, enqueued, opted_out; use with status_operator (default: equal)
• subject (optional): Filter by email subject; use with subject_operator (default: ci_contain). Use subject_operator: empty/not_empty to filter by presence of subject.
• sending_domain_id (optional): Filter by sending domain ID (number); use with sending_domain_id_operator (default: equal)
• sending_stream (optional): Filter by stream: transactional or bulk; use with sending_stream_operator (default: equal)
• events (optional): Filter by event type(s): delivery, open, click, bounce, spam, unsubscribe, soft_bounce, reject, suspension; use with events_operator (include_event / not_include_event)
• clicks_count / opens_count (optional): Filter by click/open count; use with *_operator: equal, greater_than, less_than
• client_ip / sending_ip (optional): Filter by IP; use with *_operator: equal, not_equal, contain, not_contain
• email_service_provider_response (optional): Filter by provider response text; use with *_operator (ci_contain, etc.)
• email_service_provider (optional): Filter by provider (exact); use with *_operator: equal, not_equal
• recipient_mx (optional): Filter by recipient MX; use with recipient_mx_operator (ci_contain, etc.)
• category (optional): Filter by email category; use with category_operator: equal, not_equal

All parameters are optional.

get-email-log-message

Gets a single email log message by ID (UUID): a readable summary (from, to, subject, sent time, status, category, stream, engagement, delivery context), then detailed event history. Optionally, with include_content: true, you can also load and show the message body (HTML and plain text) when Mailtrap exposes a raw message URL.

Parameters:

• message_id (required): UUID of the email log message (from send response or list-email-logs). Use list-email-logs to find message IDs.
• include_content (optional): When true, fetches the raw EML (if raw_message_url is available) and appends parsed HTML and plain-text body sections, similar to show-sandbox-email-message.

get-sending-stats

Get email sending statistics (delivery, bounce, open, click, spam rates) for a date range. Optionally break down by domain, category, email service provider, or date. Check delivery rates without leaving the editor.

Parameters:

• start_date (required): Start date for the stats range (YYYY-MM-DD)
• end_date (required): End date for the stats range (YYYY-MM-DD)
• breakdown (optional): How to break down the stats: aggregated (default), by_domain, by_category, by_email_service_provider, or by_date
• sending_domain_ids (optional): Limit results to these sending domain IDs (array of integers)
• sending_streams (optional): Limit to transactional and/or bulk (array of strings)
• categories (optional): Limit to these email categories (array of strings)
• email_service_providers (optional): Limit to these providers, e.g. Google, Yahoo, Outlook (array of strings)

create-template

Creates a new email template in your Mailtrap account.

Parameters:

• name (required): Name of the template
• subject (required): Email subject line
• html (or text is required): HTML content of the template
• text (or html is required): Plain text version of the template
• category (optional): Template category (defaults to "General")

list-templates

Lists all email templates in your Mailtrap account.

Parameters:

• No parameters required

get-template

Get a single email template by ID, including subject, category, and HTML/text body.

Parameters:

• template_id (required): ID of the template to fetch

update-template

Updates an existing email template.

Parameters:

• template_id (required): ID of the template to update
• name (optional): New name for the template
• subject (optional): New email subject line
• html (optional): New HTML content of the template
• text (optional): New plain text version of the template
• category (optional): New category for the template

[!NOTE] At least one updatable field (name, subject, html, text, or category) must be provided when calling update-template to perform an update.

delete-template

Deletes an existing email template.

Parameters:

• template_id (required): ID of the template to delete

send-sandbox-email

Sends an email to your Mailtrap test inbox for development and testing purposes. This is perfect for testing email templates without sending emails to real recipients. Supports the same two modes as send-email — inline content or template-based (template_uuid).

Parameters:

• sandbox_id (optional): Preferred. Mailtrap sandbox (test inbox) ID. Required unless MAILTRAP_SANDBOX_ID is set.
• test_inbox_id (optional): Legacy alias for sandbox_id when sandbox_id is omitted.
• from (optional): Sender as { email, name? } (a bare email string is also accepted at runtime). If not provided, DEFAULT_FROM_EMAIL is used.
• to (optional): Array of recipients as { email, name? } objects (bare email strings in the array, or a comma-separated string of plain emails, are also accepted at runtime). Optional if cc or bcc is provided; at least one of to / cc / bcc must contain a recipient.
• cc (optional): Array of CC recipients as { email, name? } objects (bare email strings also accepted at runtime).
• bcc (optional): Array of BCC recipients as { email, name? } objects (bare email strings also accepted at runtime).
• subject (conditional): Email subject line. Required for inline sends; must be omitted when template_uuid is set.
• text (conditional): Email body text. Required (alongside or instead of html) for inline sends; must be omitted when template_uuid is set.
• html (conditional): HTML version of the email body. Required (alongside or instead of text) for inline sends; must be omitted when template_uuid is set.
• category (optional): Email category for tracking. Must be omitted when template_uuid is set.
• template_uuid (optional): Use a Mailtrap email template instead of inline content. When set, subject / text / html / category must be omitted.
• template_variables (optional): Object of variables substituted into the template referenced by template_uuid. Only allowed together with template_uuid.

batch-send-sandbox-email

Sends a batch of emails to your Mailtrap test inbox in one API call, without delivering to real recipients. Same base + requests[] shape, validation, and inline-vs-template rules as batch-send-transactional-email — the difference is that this tool routes the call through the sandbox endpoint for a single test inbox.

Parameters:

• sandbox_id (optional): Mailtrap sandbox (test inbox) ID. Required unless MAILTRAP_SANDBOX_ID is set; pass per call to target a specific sandbox.
• base (optional), requests (required): See batch-send-transactional-email above.

[!NOTE] Most sandbox tools take sandbox_id (or fall back to MAILTRAP_SANDBOX_ID; legacy env MAILTRAP_TEST_INBOX_ID still works). send-sandbox-email, get-sandbox-messages, and show-sandbox-email-message also accept legacy test_inbox_id. get-sandbox-inbox, update-sandbox-inbox, delete-sandbox-inbox, and clean-sandbox-inbox use sandbox_id with legacy inbox_id (same ID; inbox_id is not used on message tools). Inbound email tools use inbox_id for a different product (received mail), not the sandbox.

get-sandbox-messages

Retrieves a list of messages from your Mailtrap test inbox. Useful for checking what emails have been received in your sandbox during testing.

Parameters:

• sandbox_id (optional): Preferred. Sandbox (test inbox) ID unless MAILTRAP_SANDBOX_ID is set.
• test_inbox_id (optional): Legacy alias for sandbox_id.
• page (optional): Page number for pagination (minimum: 1)
• last_id (optional): Pagination using last message ID. Returns messages after the specified message ID (minimum: 1)
• search (optional): Search query to filter messages

[!NOTE] Inbox ID parameters are optional when MAILTRAP_SANDBOX_ID is set. If none of sandbox_id, test_inbox_id, or env are provided, the call fails. Pagination: use page, last_id, or search as needed.

show-sandbox-email-message

Shows detailed information and content of a specific email message from your Mailtrap test inbox, including HTML and text body content.

Parameters:

• sandbox_id (optional): Preferred. Sandbox (test inbox) ID unless MAILTRAP_SANDBOX_ID is set.
• test_inbox_id (optional): Legacy alias for sandbox_id.
• message_id (required): ID of the sandbox email message to retrieve

[!NOTE] Use get-sandbox-messages first to get message IDs, then this tool for full content.

get-sandbox-project

Get a sandbox project by ID, including its inboxes and email counts.

Parameters:

• project_id (required): ID of the project to fetch

update-sandbox-project

Rename an existing sandbox project.

Parameters:

• project_id (required): ID of the project to update
• name (required): New name for the project (2–100 characters)

list-sandboxes

List every sandbox accessible to the API token across all projects.

Parameters:

• No parameters required

mark-sandbox-as-read

Mark all messages in a sandbox as read.

Parameters:

• sandbox_id (required): ID of the sandbox to act on

reset-sandbox-credentials

Reset the SMTP credentials for a sandbox. Returns the new username/password.

Parameters:

• sandbox_id (required): ID of the sandbox to act on

enable-sandbox-email-address

Enable the receive-by-email address for a sandbox (turns on the Mailtrap address that delivers messages to the sandbox via SMTP).

Parameters:

• sandbox_id (required): ID of the sandbox to act on

reset-sandbox-email-address

Generate a new receive-by-email address for a sandbox.

Parameters:

• sandbox_id (required): ID of the sandbox to act on

forward-sandbox-message

Forward a sandbox message to an external email address. Counts against your monthly forwarding quota.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message to forward
• email (required): Email address to forward the message to

update-sandbox-message

Mark a sandbox message as read or unread.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message to update
• is_read (required): true marks as read, false marks as unread

delete-sandbox-message

Delete a single sandbox message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message to delete

get-sandbox-message-spam-score

Get the SpamAssassin spam report for a sandbox message (score, rules, full report). Standalone alternative to include_spam_report: true on show-sandbox-email-message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-html-analysis

Get the HTML analysis report for a sandbox message (client compatibility scores, problematic elements). Standalone alternative to include_html_analysis: true on show-sandbox-email-message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-headers

Get the parsed mail headers for a sandbox message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-html

Get the rendered HTML body of a sandbox message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-text

Get the plain-text body of a sandbox message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-raw

Get the raw, MIME-formatted message (headers + body) for a sandbox message.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-eml

Get the message rendered as an EML file payload (suitable for attaching to a ticket or importing into another mail client).

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-message-html-source

Get the unrendered HTML source of a sandbox message (HTML before any Mailtrap-side transformations like CID-link rewrites).

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

list-sandbox-attachments

List all attachments on a sandbox message (filename, content type, size, download path).

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message

get-sandbox-attachment

Get metadata and download URL for a single attachment.

Parameters:

• sandbox_id (optional): Sandbox ID. Falls back to MAILTRAP_SANDBOX_ID.
• message_id (required): ID of the sandbox message that contains the attachment
• attachment_id (required): ID of the attachment to fetch

list-sending-domains

List sending domains and their DNS verification status.

Parameters:

• No parameters required

get-sending-domain

Get a sending domain by ID and its verification status (including DNS records). Optionally include DNS setup instructions by setting include_setup_instructions to true.

Parameters:

• sending_domain_id (required): Sending domain ID
• include_setup_instructions (optional): If true, append DNS setup instructions to the response. Default: false

create-sending-domain

Create a new sending domain. After creation, add DNS records to verify the domain (use get-sending-domain with include_setup_instructions: true to see the records).

Parameters:

• domain_name (required): Domain name (e.g. example.com)

update-sending-domain

Update a sending domain's tracking and inbound settings.

Parameters:

• sending_domain_id (required): Sending domain ID
• open_tracking_enabled (optional): Track opens on emails sent from this domain
• click_tracking_enabled (optional): Track clicks on links in emails sent from this domain
• tracking_opt_out_enabled (optional): Add the tracking opt-out link to tracked emails. Requires open or click tracking
• auto_unsubscribe_link_enabled (optional): Automatically add an unsubscribe link to emails
• inbound_enabled (optional): Allow the domain to be attached to an inbound inbox as a catch-all

At least one setting besides sending_domain_id must be provided.

delete-sending-domain

Delete a sending domain.

Parameters:

• sending_domain_id (required): Sending domain ID to delete

send-sending-domain-setup-instructions

Email DNS setup instructions for a sending domain to a given address. Useful for forwarding DNS records to a DevOps teammate.

Parameters:

• sending_domain_id (required): Sending domain ID
• email (required): Email address to send DNS setup instructions to

get-company-info

Get the company info of a sending domain, used for domain compliance verification.

Parameters:

• sending_domain_id (required): Sending domain ID

create-company-info

Set the company info of a sending domain, required for domain compliance verification.

Parameters:

• sending_domain_id (required): Sending domain ID
• name (required): Company or individual name
• address (required): Street address
• city (required): City
• country (required): Country
• zip_code (required): ZIP or postal code
• website_url (required): Company website URL
• phone (optional): Phone number
• privacy_policy_url (optional): URL of the privacy policy page
• terms_of_service_url (optional): URL of the terms of service page
• info_level (optional): business or individual

update-company-info

Update the company info of a sending domain.

Parameters:

• sending_domain_id (required): Sending domain ID
• Every field of create-company-info, all optional. At least one must be provided; fields left out are unchanged.

list-suppressions

List or search suppressions (hard bounces, spam complaints, unsubscriptions, manual imports). Returns up to 1000 results per call.

Parameters:

• email (optional): Email filter. Returns only suppressions matching this address.

create-suppression

Add an email address to the account's suppression list, so Mailtrap stops delivering to it.

Parameters:

• email (required): Email address to suppress
• domain_id (required): ID of the sending domain the suppression applies to
• sending_stream (required): transactional or bulk
• type (optional): hard bounce, spam complaint, unsubscription or manual import. Defaults to manual import

delete-suppression

Delete a suppression by ID. Mailtrap will resume delivery to this email unless it gets suppressed again.

Parameters:

• suppression_id (required): ID of the suppression to delete

list-tracking-opt-outs

List email addresses excluded from open and click tracking. Returns up to 1000 records per call.

Parameters:

• email (optional): Email filter. Returns only opt-outs matching this address
• start_time (optional): Only opt-outs created at or after this time (ISO 8601)
• end_time (optional): Only opt-outs created at or before this time (ISO 8601)
• last_id (optional): Pagination cursor — the last_id from the previous response

create-tracking-opt-out

Exclude an email address from open and click tracking for a sending domain.

Parameters:

• email (required): Email address to opt out of tracking
• domain_id (required): ID of the sending domain the opt-out applies to

delete-tracking-opt-out

Remove an email address from the tracking opt-out list, so open and click tracking applies to it again.

Parameters:

• tracking_opt_out_id (required): ID of the tracking opt-out to delete

list-webhooks

List all webhooks configured for the account. Returns the full webhook records as JSON.

Parameters:

• No parameters required

get-webhook

Get a single webhook by ID. Returns the full webhook record as JSON. Note: signing_secret is not returned here — it is only available in the response from create-webhook.

Parameters:

• webhook_id (required): ID of the webhook to fetch

create-webhook

Create a webhook. The response includes a signing_secret for verifying webhook payload signatures — this secret is returned only on creation, so store it now. If you lose it, recreate the webhook.

Parameters:

• url (required): URL Mailtrap will POST webhook events to
• webhook_type (required): "email_sending", "audit_log", or "inbound_receiving"
• active (optional, boolean): defaults to true
• payload_format (optional): "json" or "jsonlines". Defaults to "json"
• sending_stream (optional, email_sending only): "transactional" or "bulk"
• event_types (optional, email_sending only): array of delivery, soft_bounce, bounce, suspension, unsubscribe, open, spam_complaint, click, reject
• domain_id (optional, email_sending only): sending domain ID to scope this webhook to
• inbound_inbox_id (optional, inbound_receiving only): ID of the inbound inbox the webhook is linked to; omit to apply to all inboxes in the account

update-webhook

Update a webhook's mutable fields. webhook_type, sending_stream, and domain_id cannot be changed after creation — recreate the webhook if you need to change those.

Parameters:

• webhook_id (required): ID of the webhook to update
• url (optional): New webhook URL
• active (optional, boolean): Enable or disable the webhook
• payload_format (optional): "json" or "jsonlines"
• event_types (optional, email_sending only): array of delivery, soft_bounce, bounce, suspension, unsubscribe, open, spam_complaint, click, reject
• inbound_inbox_id (optional, inbound_receiving only): ID of the inbound inbox the webhook is linked to

delete-webhook

Permanently delete a webhook by ID. Returns the deleted webhook record.

Parameters:

• webhook_id (required): ID of the webhook to delete

get-contact

Get a contact by ID or email. Returns the full contact record (list memberships, status, custom fields).

Parameters:

• contact_identifier (required): Contact ID or email address

create-contact

Create a new contact.

Parameters:

• email (required): Email address
• fields (optional): Custom field values keyed by merge tag (e.g. first_name). String, number, or boolean values
• list_ids (optional): IDs of contact lists to subscribe this contact to
• unsubscribed (optional, boolean): Create the contact in unsubscribed status

update-contact

Update an existing contact identified by ID or email. list_ids replaces the contact's full membership set; list_ids_included/list_ids_excluded add/remove without disturbing the rest.

Parameters:

• contact_identifier (required): Contact ID or email
• email (optional): New email address
• fields (optional): Custom field values keyed by merge tag
• list_ids (optional): Replace membership set with this exact list
• list_ids_included (optional): List IDs to add (additive)
• list_ids_excluded (optional): List IDs to remove
• unsubscribed (optional, boolean): Set to unsubscribed (true) or subscribed (false)

delete-contact

Permanently delete a contact by ID or email. Returns the deleted contact record when the API responds with one; otherwise returns a confirmation payload.

Parameters:

• contact_identifier (required): Contact ID or email

create-contact-event

Record a contact event against a contact (by ID or email). Used to trigger contact-list automations.

Parameters:

• contact_identifier (required): Contact ID or email
• name (required): Event name (matches automation triggers)
• params (required): Object of arbitrary key/value pairs. Values may be string, number, boolean, or null

list-contact-lists

List all contact lists for the account.

Parameters:

• search (optional): Filter contact lists by name (case-insensitive match), e.g. news

get-contact-list

Get a contact list by ID.

Parameters:

• list_id (required): ID of the contact list to fetch

create-contact-list

Create a new contact list.

Parameters:

• name (required): Name for the new list

update-contact-list

Rename an existing contact list.

Parameters:

• list_id (required): ID of the contact list
• name (required): New name for the list

delete-contact-list

Permanently delete a contact list by ID.

Parameters:

• list_id (required): ID of the contact list to delete

list-contact-fields

List all contact field definitions for the account.

Parameters:

• No parameters required

get-contact-field

Get a contact field definition by ID.

Parameters:

• field_id (required): ID of the contact field

create-contact-field

Create a new contact field definition. merge_tag must be unique within the account and is used as the placeholder name in template variables.

Parameters:

• name (required): Display name (e.g. "First Name")
• merge_tag (required): Unique placeholder name (e.g. first_name)
• data_type (required): One of text, number, boolean, date

update-contact-field

Update a contact field definition. Any combination of name, merge_tag, and data_type can be changed.

Parameters:

• field_id (required): ID of the contact field
• name (optional): New display name
• merge_tag (optional): New merge tag (must remain unique)
• data_type (optional): One of text, number, boolean, date

delete-contact-field

Permanently delete a contact field definition by ID.

Parameters:

• field_id (required): ID of the contact field to delete

create-contact-import

Bulk import contacts. Returns an import job record; poll its status with get-contact-import.

Parameters:

• contacts (required): Array of contact entries. Each entry needs:
  • email (required): Contact email address
  • fields (optional): Custom field values keyed by merge tag (string or number values)
  • list_ids_included (optional): List IDs to add the contact to
  • list_ids_excluded (optional): List IDs to remove the contact from

get-contact-import

Get the status of a contact import job (created/started/finished/failed) with created/updated/over-limit counts.

Parameters:

• import_id (required): ID of the contact import job

create-contact-export

Export contacts matching a set of AND-combined filters. Returns an export job record; poll status with get-contact-export to retrieve the download URL once status is finished.

Parameters:

• filters (required): Array of filter objects. Each has:
  • name (required): Field to filter on (list_id, subscription_status, email, etc.)
  • operator (required): One of equal, not_equal, contains, not_contains, is_empty, is_not_empty
  • value (required): Comparison value (string, number, boolean, or array)

get-contact-export

Get the status of a contact export job. Once status is finished, the url field holds the CSV download link.

Parameters:

• export_id (required): ID of the contact export job

list-email-campaigns

List the account's email campaigns, newest first, with page-token pagination. Optionally filter by name with search.

Parameters:

• token (optional): Page number to retrieve (page-token pagination). Defaults to 1
• per_page (optional): Number of campaigns per page. Defaults to 50, maximum 100
• search (optional): Filter campaigns by name (case-insensitive partial match)

get-email-campaign

Get an email campaign by ID.

Parameters:

• email_campaign_id (required): ID of the email campaign

create-email-campaign

Create a new email campaign. The campaign is always created in the draft state; scheduling and starting are separate tools (schedule-email-campaign, start-email-campaign).

Parameters:

• name (required): Campaign name
• domain_id (required): ID of the verified sending domain used for the campaign, as returned by the Sending Domains endpoints
• from_local_part (required): Local part (before the @) of the From address
• template_attributes (required): Inline email template. Has:
  • subject (required): Email subject line (max 255 chars). Supports merge tags, e.g. Hi {{first_name}}
  • body_html (optional): HTML body (the design). Required before the campaign can be scheduled or started. Include an unsubscribe link via an anchor whose href contains the __unsubscribe_url__ placeholder
  • body_text (optional): Plain-text alternative of the email body
  • merge_tags (optional): Bare names of the merge tags referenced in the subject/body, e.g. ["first_name"]
• from_display_name (optional): Display name shown in the From header
• reply_to (optional): Reply-To address parts (display_name, local_part, domain)
• delivery_mode (optional): rapid (send as fast as possible) or gradual (throttle to delivery_options.emails_per_hour)
• delivery_options (optional): Delivery throttling options (emails_per_hour)
• contact_list_ids (optional): IDs of contact lists to send to (treated as the full set of included lists)
• contact_segment_ids (optional): IDs of contact segments to send to (treated as the full set of included segments)

update-email-campaign

Update a draft email campaign. Only the provided fields change; the template is edited in place. Campaigns in any other state cannot be updated.

Parameters:

• email_campaign_id (required): ID of the email campaign to update
• All other parameters are optional and identical to create-email-campaign (name, domain_id, from_local_part, from_display_name, reply_to, template_attributes, delivery_mode, delivery_options, contact_list_ids, contact_segment_ids)

delete-email-campaign

Delete an email campaign by ID. Only a campaign in the draft state can be deleted.

Parameters:

• email_campaign_id (required): ID of the email campaign to delete

start-email-campaign

Start sending a draft email campaign immediately. Only draft campaigns can be started; the template must have a body_html design and the audience and verified sending domain must be set.

Parameters:

• email_campaign_id (required): ID of the email campaign to start

schedule-email-campaign

Schedule a draft email campaign to start sending at a future time. Only draft campaigns can be scheduled.

Parameters:

• email_campaign_id (required): ID of the email campaign to schedule
• datetime (required): When to send the campaign (ISO 8601). Must be in the future and no more than 1 month ahead

cancel-email-campaign

Cancel a scheduled email campaign, returning it to draft. Only scheduled campaigns can be cancelled.

Parameters:

• email_campaign_id (required): ID of the email campaign to cancel

terminate-email-campaign

Terminate an email campaign that is currently sending (started, queued, or paused), aborting the in-flight send.

Parameters:

• email_campaign_id (required): ID of the email campaign to terminate

reset-email-campaign

Reset a scheduled email campaign back to draft. Only scheduled campaigns can be reset.

Parameters:

• email_campaign_id (required): ID of the email campaign to reset

get-email-campaign-stats

Get aggregated performance statistics for an email campaign (counts and rates for deliveries, opens, clicks, bounces, spam complaints, and unsubscriptions).

Parameters:

• email_campaign_id (required): ID of the email campaign
• start_date (optional): Start of the aggregation window (inclusive), YYYY-MM-DD. Defaults to the day the campaign was last started
• end_date (optional): End of the aggregation window (inclusive), YYYY-MM-DD. Defaults to the current date

list-accounts

List Mailtrap accounts the current API token can access, with each account's access levels.

Parameters:

• No parameters required

get-billing-usage

Get the current billing cycle usage for the account: sending and testing plans, limits, and current counts.

Parameters:

• No parameters required

list-account-accesses

List account accesses (users, invites, API tokens) for the account. Optional filters narrow the result to specific resources. Requires account admin/owner permissions.

Parameters:

• domain_uuids (optional): Filter by sending domain UUIDs (array of strings)
• inbox_ids (optional): Filter by sandbox inbox IDs (array of strings)
• project_ids (optional): Filter by sandbox project IDs (array of strings)

remove-account-access

Remove an account access by ID. For User specifiers this revokes their permissions; for Invite or ApiToken specifiers it removes the specifier entirely. Requires admin/owner.

Parameters:

• account_access_id (required): ID of the access record to remove

get-permission-resources

Get all resources (inboxes, projects, domains, billing, account) to which the API token has admin access, nested by hierarchy.

Parameters:

• No parameters required

bulk-update-permissions

Bulk create, update, or destroy permissions for a single account access. Existing (resource_type, resource_id) pairs are updated; new ones are created. Set destroy: true on an entry to remove it.

Parameters:

• account_access_id (required): Target account access ID
• permissions (required): Array of permission entries. Each has:
  • resource_id (required): Resource ID (number or string)
  • resource_type (required): One of account, project, inbox, domain, billing
  • access_level (optional): admin/100 or viewer/10
  • destroy (optional, boolean): When true, removes this permission instead of creating/updating it

list-api-tokens

List all API tokens for the account.

Parameters:

• No parameters required

create-api-token

Create a new API token. The response includes the secret token value — this is the only time the full token is returned, so store it immediately. If you lose it, recreate the token.

Parameters:

• name (required): Display name for the token
• expires_at (optional): Token expiration as an ISO 8601 date-time. Omit for the server default (1 year); pass an explicit null for a token that never expires. Past values or values more than 5 years ahead are rejected
• resources (optional): Array of resource permissions to scope the token to. Each entry has:
  • resource_type (required): One of account, project, inbox, domain, billing
  • resource_id (required): ID of the resource
  • access_level (required): 100 (admin) or 10 (viewer)

get-api-token

Get an API token by ID. Returns metadata only — the secret token value is not returned here (only from create-api-token / reset-api-token).

Parameters:

• api_token_id (required): ID of the API token

reset-api-token

Reset (rotate) an API token by ID. The response includes the new secret token value — returned only on this call, so store it immediately. The previous token is invalidated.

Parameters:

• api_token_id (required): ID of the API token to reset
• expires_at (optional): Expiration for the new token as an ISO 8601 date-time. Omit for the server default (1 year); pass an explicit null for a token that never expires. Past values or values more than 5 years ahead are rejected

delete-api-token

Permanently delete an API token by ID. The token can no longer authenticate after deletion.

Parameters:

• api_token_id (required): ID of the API token to delete

list-sub-accounts

List sub-accounts in the organization. Requires MAILTRAP_ORGANIZATION_ID env var and sub-account management permissions.

Parameters:

• No parameters required

create-sub-account

Create a new sub-account under the organization. Requires MAILTRAP_ORGANIZATION_ID env var and sub-account management permissions.

Parameters:

• name (required): Display name for the new sub-account

list-inbound-folders

List all inbound folders in the account. Returns a formatted summary.

Parameters:

• No parameters required

get-inbound-folder

Get a single inbound folder by ID. Returns the full folder record as JSON.

Parameters:

• folder_id (required): ID of the inbound folder

create-inbound-folder

Create a new inbound folder.

Parameters:

• name (required): The folder name

update-inbound-folder

Rename an inbound folder.

Parameters:

• folder_id (required): ID of the inbound folder
• name (required): The new folder name

delete-inbound-folder

Permanently delete an inbound folder along with all of its inboxes.

Parameters:

• folder_id (required): ID of the inbound folder

list-inbound-inboxes

List all inboxes in an inbound folder. Returns a formatted summary.

Parameters:

• folder_id (required): ID of the inbound folder

get-inbound-inbox

Get a single inbound inbox by ID. Returns the full inbox record as JSON.

Parameters:

• folder_id (required): ID of the inbound folder
• inbox_id (required): ID of the inbox

create-inbound-inbox

Create a new inbound inbox in a folder.

Parameters:

• folder_id (required): ID of the inbound folder
• name (required): The inbox name
• domain_id (optional): Attach to a custom sending domain (catch-all inbox). Omit for a Mailtrap-hosted inbox

update-inbound-inbox

Rename an inbound inbox.

Parameters:

• folder_id (required): ID of the inbound folder
• inbox_id (required): ID of the inbox
• name (required): The new inbox name

delete-inbound-inbox

Permanently delete an inbound inbox.

Parameters:

• folder_id (required): ID of the inbound folder
• inbox_id (required): ID of the inbox

list-inbound-messages

List received messages in an inbound inbox (cursor-paginated). Returns a formatted summary with a next-page hint when more results exist.

Parameters:

• inbox_id (required): ID of the inbox
• last_id (optional): Pagination cursor from a previous response's last_id

get-inbound-message

Get a single inbound message with its full body and attachment download URLs. Returns the full message record as JSON.

Parameters:

• inbox_id (required): ID of the inbox
• message_id (required): ID of the message

delete-inbound-message

Permanently delete an inbound message.

Parameters:

• inbox_id (required): ID of the inbox
• message_id (required): ID of the message

reply-to-inbound-message

Reply to an inbound message (sends to the original sender). Sends a real email. Addresses accept a bare email string or { email, name? }.

Parameters:

• inbox_id (required): ID of the inbox
• message_id (required): ID of the message to reply to
• text / html (at least one recommended): Reply body
• from (optional): Sender. Rejected for Mailtrap-hosted inboxes; required for custom-domain inboxes
• cc / bcc / reply_to (optional): Additional addresses
• category (optional): Message category
• attachments (optional): Array of { content (base64), filename, type?, disposition?, content_id? }
• headers / custom_variables (optional): Objects of string values

reply-all-to-inbound-message

Reply to an inbound message and copy the original's other recipients. Sends a real email. Same parameters as reply-to-inbound-message.

Parameters:

• inbox_id (required): ID of the inbox
• message_id (required): ID of the message to reply to
• Plus the same optional send fields as reply-to-inbound-message

forward-inbound-message

Forward an inbound message to new recipients. Sends a real email.

Parameters:

• inbox_id (required): ID of the inbox
• message_id (required): ID of the message to forward
• to (required): At least one recipient (bare email string or { email, name? }, or an array)
• Plus the same optional send fields as reply-to-inbound-message

list-inbound-threads

List conversation threads in an inbound inbox (cursor-paginated). Returns a formatted summary with a next-page hint when more results exist.

Parameters:

• inbox_id (required): ID of the inbox
• last_id (optional): Pagination cursor from a previous response's last_id

get-inbound-thread

Get a single inbound thread with its messages embedded (oldest first). Returns the full thread record as JSON.

Parameters:

• inbox_id (required): ID of the inbox
• thread_id (required): ID of the thread

delete-inbound-thread

Permanently delete an inbound thread.

Parameters:

• inbox_id (required): ID of the inbox
• thread_id (required): ID of the thread

Development

1. Clone the repository:

git clone https://github.com/mailtrap/mailtrap-mcp.git
cd mailtrap-mcp

2. Install dependencies:

npm install

Configuration with Claude Desktop or Cursor

[!TIP] See the location of the config file in the Setup section.

Add the following configuration:

{
  "mcpServers": {
    "mailtrap": {
      "command": "node",
      "args": ["/path/to/mailtrap-mcp/dist/index.js"],
      "env": {
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "[email protected]",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
      }
    }
  }
}

If you are using asdf for managing Node.js you should use absolute path to executable:

(example for Mac)

{
  "mcpServers": {
    "mailtrap": {
      "command": "/Users/<username>/.asdf/shims/node",
      "args": ["/path/to/mailtrap-mcp/dist/index.js"],
      "env": {
        "PATH": "/Users/<username>/.asdf/shims:/usr/bin:/bin",
        "ASDF_DIR": "/opt/homebrew/opt/asdf/libexec",
        "ASDF_DATA_DIR": "/Users/<username>/.asdf",
        "ASDF_NODEJS_VERSION": "20.6.1",
        "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
        "DEFAULT_FROM_EMAIL": "[email protected]",
        "MAILTRAP_ACCOUNT_ID": "your_account_id",
        "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
      }
    }
  }
}

VS Code

[!TIP] See the location of the config file in the Setup section.

{
  "mcp": {
    "servers": {
      "mailtrap": {
        "command": "node",
        "args": ["/path/to/mailtrap-mcp/dist/index.js"],
        "env": {
          "MAILTRAP_API_TOKEN": "your_mailtrap_api_token",
          "DEFAULT_FROM_EMAIL": "[email protected]",
          "MAILTRAP_ACCOUNT_ID": "your_account_id",
          "MAILTRAP_SANDBOX_ID": "your_sandbox_id"
        }
      }
    }
  }
}

Testing

Running tools against real Mailtrap

There are two ways to exercise a tool end-to-end against a real Mailtrap account: the MCP Inspector browser UI for interactive exploration, or its CLI mode for one-shot calls from the shell.

Both require the bundle to be built first:

npm run build

and MAILTRAP_API_TOKEN + MAILTRAP_ACCOUNT_ID exported in your shell (the mcp:cli script forwards both to the spawned server).

Browser UI

npm run dev

The Inspector prints a URL like http://localhost:6274. Open it, switch to the Tools tab, pick a tool (e.g. get-template), fill the parameters as JSON, and hit Run. The Mailtrap response appears in the panel below.

CLI

For one-shot calls without the UI, use npm run mcp:cli. Pass the Inspector's CLI flags after -- so npm forwards them verbatim:

# List all tools
npm run mcp:cli -- --method tools/list

# Call a tool — flags after the `--`
npm run mcp:cli -- \
  --method tools/call \
  --tool-name get-template \
  --tool-arg template_id=12345

# Multiple --tool-arg flags for tools with several params
npm run mcp:cli -- \
  --method tools/call \
  --tool-name send-sending-domain-setup-instructions \
  --tool-arg sending_domain_id=3938 \
  --tool-arg [email protected]

Running the MCPB Server

# Run the MCPB server directly
node dist/mcpb-server.js

# Or use the provided binary
mailtrap-mcpb-server

[!TIP] For development with the MCP Inspector:

npm run dev:mcpb

Error Handling

This server uses structured error handling aligned with MCP conventions:

• VALIDATION_ERROR: Input validation failures
• CONFIGURATION_ERROR: Missing or invalid configuration
• EXECUTION_ERROR: Runtime execution errors
• TIMEOUT: Operation timeout (30 seconds default)

Errors include actionable messages and are logged in structured form.

Security

• Input validated via Zod schemas
• Environment variables handled securely
• Timeout protection on operations (30 seconds)
• Sensitive details sanitized in error output

Logging

Structured JSON logs with levels: INFO, WARN, ERROR, DEBUG.

Enable debug logging by setting DEBUG=true.

# Example: enable debug logging
DEBUG=true node dist/mcpb-server.js

Important: The server writes logs to stderr so stdout remains reserved for JSON-RPC frames. This prevents hosts from encountering JSON parsing errors due to interleaved logs.

Log analysis example using jq:

# Filter error logs
node dist/mcpb-server.js 2>&1 | jq 'select(.level == "error")'

# Filter debug logs
node dist/mcpb-server.js 2>&1 | jq 'select(.level == "debug")'

Troubleshooting

Common issues:

1. Missing API Token: ensure MAILTRAP_API_TOKEN is set
2. Sandbox not working: provide sandbox_id in the tool call (or legacy test_inbox_id on send/list/show message tools), or set MAILTRAP_SANDBOX_ID env
3. Timeout errors: check network connectivity and Mailtrap API status
4. Validation errors: ensure all required fields are provided

Contributing

Bug reports and pull requests are welcome on GitHub. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The package is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Mailtrap project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.