Configure sendmail

Mailpit requires messages to be delivered via SMTP. Emails can come directly from and email client (eg: Thunderbird), or via a mail transfer agent (MTA) such as sendmail (which is commonly used with applications such as PHP). Mailpit has its own implementation of sendmail for convenience (by default delivering to localhost:1025 instead of localhost:25), however you can theoretically use any existing sendmail client, provided it allows you to set the delivery host & port.

There are several different options available:

Use the mailpit binary directly

You can use mailpit sendmail as your sendmail configuration in php.ini:

sendmail_path = /usr/local/bin/mailpit sendmail

If your Mailpit server is not running on the default 1025 port or on another machine, then this can be set by adding -S <host>:<port> to the sendmail command.

Symlink to the mailpit binary

If Mailpit is found on the same host as sendmail, you can symlink the Mailpit binary to sendmail, eg: ln -s /usr/local/bin/mailpit /usr/sbin/sendmail (only if Mailpit is running on default 1025 port).

Use a system-installed sendmail binary

You can use your default system sendmail binary to route directly to port 1025 (configurable) by calling /usr/sbin/sendmail -S localhost:1025 -t. This may vary depending on which implementation of sendmail you are using, and whether it allows you to configure the port.

Compile Mailpit’s sendmail implementation

You can build a Mailpit-specific sendmail binary from source (see building from source).

Mailpit’s sendmail options

Mailpit’s sendmail works very similar to other implementations, and shares several of the common flags (even if most are ignored and simply exist for compatibility).

To view all options, see mailpit sendmail -h

Usage: mailpit sendmail [flags] [recipients] < message

Flags:
  -S  string  SMTP server address (default "localhost:1025")
  -f  string  Set the envelope sender address (default "user@host")
  -bs         Handle SMTP commands on standard input
  -t          Ignored
  -i          Ignored
  -o          Ignored
  -v          Ignored

Settings via the environment

The server for Mailpit’s sendmail implementation can also be set using the environment variable MP_SENDMAIL_SMTP_ADDR=mailpit:1025, and the “from” (bounce) address via MP_SENDMAIL_FROM=user@host.

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