We have a mail server running Zimbra (ZCS 6.0.8). The server has 5 active public IP addresses in the same subnet. (
.230). I currently have
A records for each of these (
host4.domain.com), with the main
host.domain.com of the machine pointing to
Our host has ended up being listed on the SORBS DUHL list (even though it's in a server farm). According to them you can get removed quickly by checking that your host has an
MX record, an
A record, and a
PTR record that points back to the hostname given in the
I tried setting the
PTR records so that each of these addresses resolved back to their
A record (i.e.
.228 had a
host2.domain.com). However, I then got mail being rejected from other servers because when Postfix (under Zimbra control) sends out mail, it uses the main hostname for the
HELO - there doesn't seem to be any way to override it. So the
PTR records currently say
host.domain.com for all 5 IP addresses.
What's the correct way to handle this? Should I have an
A record for the domain that points to all the IP addresses (for round-robin handling)? I'm nervous of changes that could cause problems, so I'm wondering what the standard way to handle a multiple-IP-address mail server is.