2nd mail server adding to the mix
 

Afternoon all, we have an older box which hosts all our corporate mail, but he's a bit old, small hard drive, etc. We have a new app which sends a lot of mail and 2 weekends in a row has killed the box.

So I want to play a bit with postfix, and have it installed and ready. The main question is can I have him 'send' all the mail out but keep the incoming since it's not much going to the primary? Naturally it's yes, but what do I need to look at record wise?

I know there are new things like spf, spoofing, etc and when someone get's that message from admin@domain.com, there servers naturally reverse lookup, but he won't be the box that receives for that domain so will it simply not accept?

This is an old windows mail server set in it's ways, but both DNS and the new sending mail server is running under linux.

Thanks

Sure, just set your internal servers to use the postfix server as the mail relay instead of the old one. You don't have to change anything externally if you're still receiving mail on the old one.

This depends a great deal on how things are configured. If you "Old Mail box" and your "New Mail Box" each have Internet addresses, then you may have to adjust your SPF records and in fact your DNS records so that others will accept mail from the "New Mail Box".

You can get help setting up your SPF record here:
http://old.openspf.org/wizard.html

On the other hand if your boxes are both NATed and share the same external address then changes needed should be minimal.

Actually completely forgot until I started looking at that spf URL. ALL our incoming mail goes through postini, so the MX records all goto s8a1.psmtp.com, and the other google ones, not sure how that changes the dynamics, but will still read more.