I'm trying to set up a Postfix server on Google Cloud, which blocks outgoing SMTP ports. My problem is that one email address (say
firstname.lastname@example.org) needs to be an alias for an external email address (
email@example.com); all emails sent to firstname.lastname@example.org need to be forwarded to email@example.com. I also have other email addresses that simply need to be delivered locally.
I am able to get Postfix to attempt to send all emails to firstname.lastname@example.org to email@example.com using virtual alias mappings, but because SMTP ports are blocked, the connection doesn't go through to example2.com's SMTP server. I want to get Postfix to send these emails through Mailjet on port 2525 so that the connection isn't blocked. Unfortunately, even when
relayhost is set to
in-v3.mailjet.com:2525, Postfix doesn't attempt to relay the emails and instead tries to send them directly.
I'm on Ubuntu 16.04.