smtp_auth_proxy – SMTP Authentication Proxy

March 26, 2020

**Configuration Change. ** This feature is available in Momentum 4.2 and later.

The smtp_auth_proxy module allows your edge SMTP servers to forward SMTP AUTH requests onto one or more SMTP servers, with optional lookup of the authentication host for a particular user.

smtp_auth_proxy {
  # Host for forwarding the SMTP AUTH request.
  host = some.smtp.server
  port = 25
  timeout = 60

  # Optionally query a database to look up the SMTP server
  # for auth for a particular user.
  ds_cache = smtp_auth_proxy
  query = "SELECT host FROM auth_servers WHERE username = :username, localpart = :localpart, domain = :domain;"
}

Esmtp_Listener {
  SMTP_Extensions = ("AUTH LOGIN" XREMOTEIP XDUMPCONTEXT XCLIENT XSETCONTEXT)

  AuthLoginParameters = [
      log_authentication = "true"
      uri = "smtp_auth_proxy://"
  ]

  Listen ":25" {}
}

Note

Hosts specified by the relay_hosts option are not subject to any SMTP authentication you may have implemented. Likewise when open_relay is set to true. For more information, see relay_hosts.