go-smtpsrv

Golang provides an SMTP client implementation in the net/smtp package, but it lacks an implementation of an SMTP server. This package is based on RFC 5321 and attempts to bridge that gap.

Using go-smtpsrv

To use the package in your project, import the following package:

import "github.com/hectane/go-smtpsrv"

To begin receiving SMTP connections from clients, create an instance of smtpsrv.Server:

s, err := smtpsrv.NewServer(&smtpsrv.Config{
    Addr: ":smtp",
    Banner: "SuperAwesomeServer",
    ReadTimeout: 2 * time.Minute,
})

The banner is used to greet clients and the read timeout determines how long the server will wait for the client to send a command before timing out and disconnecting them.

The server provides a channel that must be used for receiving messages:

go func() {
    for m := range s.NewMessage {
        // do something with the message
    }
}()

To close the server and wait for it to shut down:

s.Close(false)

To shut down immediately and forcefully disconnect all clients without allowing them to finish, use true for the parameter passed to Close().