Hello,
Some users within our organisation receive NDR’s like this:
Your message did not reach some or all of the intended recipients.
Subject:
Sent: 3/10/2007 16:04
The following recipient(s) could not be reached:
info@recipientdomain.com on 3/10/2007 16:05
There was a SMTP communication problem with the recipient’s email server. Please contact your system administrator.
We have this issue only with a few mail recipients. My configuration:
Exchange 2003 SP2 with FE and BE configuration. There are 2 WAN IP’s, #1 and #2, first one is for outbound traffic, second is for inbound. When doing a reverse lookup of our #1 IP, dnsstuff.com tells us that the A record of our domain published in the PTR (=same as the HELO hostname) is not pointing back to the originating IP. But when I google a bit I found that normally there shouldn’t be any problem using different WAN IP’s on inbound and outbound. Does it maybe mean that I should publish our SMTP clients on the second IP address, or should I change our DNS configuration so that the A record points to #1 IP?
If I do a reverse lookup for the PTR of our #2 IP address, it gives us the same domain as when I do it for #1. No errors concerning A records for this reverse lookup, because the A record for this domain points back to the same IP, #2.
One last thing, if I don’t want to change any of the two options above, could an SPF record maybe help me out?
Thanks a lot for your help,
Regards,
G?nther
