On Fri, Feb 3, 2012 at 8:14 AM, Reindl Harald <h.reindl at thelounge.net> wrote: > > on both sides of the NAt you need a DNS with the correct mapping > the host on the other side is not interested in your NAT > it sees a IP, a HELO and DNS-Records > > so it is YOUR job as admin to provide the correct HELO for your > outgoing IP and even configure the DNS behind the NAT correctly > if you like it really clean Your HELO has nothing to do with your source IP, and you can't possibly expect a multi-homed server to adjust its HELO to the interface it happens across. Expecting the reverse DNS of the source IP to give a name that has the same IP in an A record lookup is somewhat different, but still I don't think that is an actual requirement. As a mail admin, you are of course free to discard your users' mail for any whimsical reason you like, but if you want to say it is a requirement, please quote the MUST in an RFC. -- Les Mikesell lesmikesell at gmail.com