Outbound SMTP via LTM

I've seen several questions about variations on this, but I can't seem to find one specifically addressing my use case.

 

I have multiple Postfix servers which are used for outbound SMTP only. (An emergency alerting system.) I would like to route all of their outbound messages through the LTM (v12.x) so that all messages exit my network via a specific IP address. I would guess that this would involve configuring my postfix main.cf with a relayhost = [VIP]:25 statement, but I don't know what sort of configuration would be required on the LTM to process the messages it receives from our servers. Can anyone point me in the right direction?

 

Ultimately, I'd like to use an iRule to standardize the headers (removing local IPs for example) but that should be comparitively simple if I can get the LTM properly inserted into the communication chain.

 

Thanks.