outgoing mail on second IP

[Guest]

[rwsh]

Hi,

I have an EFW setup with two static IPs on RED: a default of 1.2.3.4 (say) and an alias of 5.6.7.8 (say). I can receive mail fine on 5.6.7.8 but outgoing mail all originates from the default IP, 1.2.3.4. I want to force outgoing mail to be from 5.6.7.8. This is an issue because I need to have reverse DNS working correctly.

Could someone advise how to achieve this, either through the interface or by editing postfix config.

Thanks,
Roger