Sending mail

There are two methods to send emails to Mailpit:

Send via SMTP

Mailpit acts like any compliant SMTP server, by default listening unencrypted and without authentication on port 1025. The listening port, optional TLS/STARTTLS security, and SMTP authentication can be configured via runtime options.

Send via the HTTP API

Messages can alternatively be sent to Mailpit via the HTTP API in JSON format, useful for applications that do not natively support SMTP (see API documentation). This API endpoint provides most common functionality for building a message, similar to other popular services.

Send API endpoint dedicated authentication

Starting in v1.26.0, the send message endpoint (/api/v1/send) supports dedicated authentication that is independent of other API endpoints and the web UI. This allows you to configure different authentication requirements specifically for sending messages.

You can configure the send API endpoint to:

• Use dedicated credentials different from the web UI authentication
• Accept any credentials (or none) for testing environments
• Fall back to UI authentication when no send endpoint authentication is configured

This provides flexibility for integration scenarios where you want to allow message sending with different security requirements than accessing stored messages or the web interface.

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