Linux – postfix smtp relay script

linuxpostfixscripting

I have a Postfix server and using it with Outlook (POP/SMTP).

I have different sender addresses for an account.
Now I want to configure a relay for a specific sender address.
For example I have postfix for my main domain domain1.com.
Now I have a sender address that is domain2.com.

For that sender address I want that postfix to relay mail to a second SMTP server.
I think that should be possible without problems.

But the problem is that I have to create a SSH tunnel to the second server to connect to the
SMTP server.
But I cant use a persistent SSH connection so I want to know if it is possible that postfix executes some script before relaying the mail to the second SMTP server.

I already found some information for executing a script when incomming emails but I only want to establish the SSH tunnel before postfix relays the mail to the second SMTP server.

Best Answer

Exactly how you implement it is up to you, but you can create your own transport, and that transport can be a script, or daemon, etc.

If you could keep the tunnel up, it would be a breeze, you'd just set an

domain2.com smtp:127.0.0.1:2000 (or whatever port you assigned locally)

transport up.

Related Solutions

Postfix – Forcing the From Address When Relaying Over SMTP

This is how to really do it in postfix.

This config changes sender addresses from both local originated, and relayed SMTP mail traffic:

/etc/postfix/main.cf:

sender_canonical_classes = envelope_sender, header_sender
sender_canonical_maps =  regexp:/etc/postfix/sender_canonical_maps
smtp_header_checks = regexp:/etc/postfix/header_check

Rewrite envelope address from email originating from the server itself

/etc/postfix/sender_canonical_maps:

/.+/    newsender@address.com

Rewrite from address in SMTP relayed e-mail

/etc/postfix/header_check:

/From:.*/ REPLACE From: newsender@address.com

Thats very useful if you're for instance using a local relay smtp server which is used by all your multifunctionals and several applications.

If you use Office 365 SMTP server, any mail with a different sender address than the email from the authenticated user itself will simply be denied. The above config prevents this.

Ubuntu – Postfix: How to configure Postfix with virtual Dovecot mailboxes

Yes, you can't have domain in both mydestination and virtual_mailbox_maps. To overcome this you need set mydestination in main.cf

mydestination = localhost.$mydomain, localhost

and in /etc/postfix/virtual

root@domain1.com   root@localhost
webmaster@domain1.com  webmaster@localhost

with this setup, email to root@domain1.com will be redirected root@localhost. Because localhost listed in mydestination then postfix will apply alias in /etc/aliases

Best Answer

Related Solutions

Postfix – Forcing the From Address When Relaying Over SMTP

Ubuntu – Postfix: How to configure Postfix with virtual Dovecot mailboxes

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