queue/smtp_proxy plugin

This plugin delivers to another mail server. This is a common setup when you want to have a mail server with a solid pedigree of outbound delivery to other hosts, and inbound delivery to users.

In comparison to queue/smtp_forward, this plugin makes a connection at MAIL FROM time to the ongoing SMTP server. This can be a benefit in that you get any SMTP-time filtering that the ongoing server provides, in particular one important facility to some setups is recipient filtering. However be aware that other than connect and HELO-time filtering, you will have as many connections to your ongoing SMTP server as you have to Haraka.


  • smtp_proxy.ini
    Configuration is stored in this file in the following keys:
    • enable_outbound=true

    SMTP proxy outbound messages (set to false to enable Haraka's separate Outbound mail routing (MX based delivery)).
    • host=HOST
      The host to connect to.
    • port=PORT
      The port to connect to.
    • connect_timeout=SECONDS
      The maximum amount of time to wait when creating a new connection to the host. Default if unspecified is 30 seconds.
    • timeout=SECONDS
      The amount of seconds to let a backend connection live idle in the proxy pool. This should always be less than the global plugin timeout, which should in turn be less than the connection timeout.
    • max_connections=NUMBER
      Maximum number of connections to create at any given time.
    • enable_tls=true|yes|1
      Enable TLS with the forward host (if supported). TLS uses options from the tls plugin.
    • auth_type=plain|login
      Enable PLAIN or LOGIN SMTP AUTH. This is required to enable AUTH.
    • auth_user=USERNAME
      SMTP AUTH username to use.
    • auth_pass=PASSWORD
      SMTP AUTH password to use.