Setting the source port for outgoing email

[Graham Leggett]

Hi all,








inet_interfaces = $myhostname

I have a machine that is both a postfix mailserver, and a NAT router for a number of machines behind the box. Because traffic from machines behind the box can cause the mailserver's IP to be blacklisted, the mailserver machine has two IP addresses, one for the mailserver, and one for NAT. There is a problem: postfix seems to be hell bent on choosing the NAT IP address as a source IP for outgoing connections, instead of the IP address specified by inet_interfaces: According to the docs at http://www.postfix.org/postconf.5.html, "When inet_interfaces specifies just one IPv4 and/or IPv6 address that is not a loopback address, the Postfix SMTP client will use this address as the IP source address for outbound mail"

I am using postfix-2.3.3-2 as shipped with RHEL5.

Regards,
Graham
--

This doesn't seem to be happening. Instead, postfix wants to choose the other IP address (which happens to be the NAT address) on the interface, rather than IP address @myhostname, which is the first IP on the interface. Can anyone confirm whether setting the source address in postfix is even possible, and how to force postfix to use a specific IP as a source address?

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