kumomta/docs/reference/kumo/define_egress_source.md

kumo.define_egress_source {PARAMS}

Defines an egress source, which is an entity associated with the source of outbound traffic from the MTA. A source must be referenced by a pool to be useful.

This function should be called only from inside your init event handler.

A source must have at a minimum a name, which will be used in logging/reporting.

PARAMS is a lua table which may have the following keys:

name

Required string.

The name of the source. If you call kumo.define_egress_source multiple times with the same name, the most recently defined version of that name will replace any previously defined source with that name.

kumo.on('init', function()
  -- Make a source that just has a name, but otherwise doesn't
  -- specify any particular source configuration
  kumo.define_egress_source {
    name = 'example',
  }
end)

source_address

Optional string.

If set, specifies the local IP address that should be used as the source of any connection that will be made from this source.

If not specified, the kernel will select the IP address automatically.

kumo.on('init', function()
  -- Make a source that will emit from 10.0.0.1
  kumo.define_egress_source {
    name = 'ip-1',
    source_address = '10.0.0.1',
  }
end)

ehlo_domain

Optional string.

If set, specifies the hostname to be passed with the EHLO command when the server connects to a remote host.

If not specified, the kernel will use the server's hostname.

kumo.on('init', function()
  -- Make a source that will emit from 10.0.0.1
  kumo.define_egress_source {
    name = 'ip-1',
    source_address = '10.0.0.1',
    ehlo_domain = 'mta1.examplecorp.com',
  }
end)

remote_port

Optional integer.

If set, will override the remote SMTP port number. This is useful in scenarios where your network is set to manage the egress address based on port mapping.

This option takes precedence over kumo.make_egress_path().smtp_port.