Connect stage

The connect stage is the initial stage of an SMTP session, where the server and client establish a connection. It determines the hostname and greeting the server advertises, and can run a Sieve script against the incoming connection.

Connect-stage behaviour is configured on the MtaStageConnect singleton (found in the WebUI under Settings › MTA › Session › Connect Stage).

Hostname

The hostname field is an expression that returns the hostname the server uses to identify itself during the SMTP session. By default it resolves to the system hostname via system('hostname').

Greeting

The smtpGreeting field is an expression that returns the greeting message sent to the client when the SMTP session begins. The default greeting combines the system hostname with Stalwart ESMTP at your service.

Sieve script

The script field selects a Sieve script to run before the SMTP session is allowed to proceed. This is typically used to filter connections by remote IP address: an expression selects the script name at runtime, and the script itself may reject the connection based on connection-level variables such as remote_ip.

For example, setting script to the expression "'connect_filter'" runs a Sieve script named connect_filter which can inspect env.remote_ip and reject unwanted sources:

require ["variables", "reject"];

if string "${env.remote_ip}" "192.0.2.88" {
    reject "Connection from this IP is not accepted.";
}