SMTP source_ip option

Question

My server has multiple network interfaces (each with its own IP).
Due to the hosting provider's security policy, outgoing connections to SMTP (port 587) are only allowed from a specific IP address — not from the default one.

So I need to configure Drupal to send emails via SMTP using a non-default local IP.

I'm fine with using external modules such as:

• SMTP
• Symfony Mailer

However, I can’t find any option to set the local bind address (the source IP for the connection).

In other systems this can be done with something like:

'socket'=>[
      'bindto' => '1.2.3.4:0'
    ] 

or

localAddress: '1.2.3.4'

or

'source_ip' => '1.2.3.4',

Has anyone encountered this before or found a way to set the source IP for outgoing SMTP connections in Drupal (or in Symfony Mailer settings)?

Answer 1

I added a new option to drupal/smtp module. See https://www.drupal.org/project/smtp/issues/3553774