PowerMTA: How to forward messages to external SMTP servers

Question

We have a PowerMTA server that receives incoming e-mail. Is it possible to forward specific domains to another existing SMTP server that's not running PowerMTA?

The solution that I found so far is to pipe the e-mails to mailx that's pointing to another SMTP server, but this looks hack-ish.

Thanks!

Answer 1

This is an example for routing gmail.com to SendGrid. You might need to uncomment use-unencrypted-plain-auth for some SMTP providers.

<domain gmail.com>
    queue-to sendgrid.rollup
</domain>

<domain sendgrid.rollup>
#   use-unencrypted-plain-auth yes
    auth-username username
    auth-password password
    route smtp.sendgrid.net:587
    use-starttls yes
    require-starttls yes
</domain>

You might want to use virtual-mta and virtual-mta-pool if you are looking to use multiple SMTP providers to load balance outgoing emails. Let me know and I will update answer with its configuration.