New Email Setup- Undeliverable Mail

StarTrek4U

Gawd
Joined
Jan 8, 2003
Messages
1,011
So we just recently migrated to an in-house email solution using Exchange 2007 and an Ironport C150 for our edge spam/av device. For the most part everything seems to be going fine however there are a number of recipients that when we try to send email to we get a bounceback that looks like this:

[email protected]
[167.xxx.xxx.xxx] #<[167.xxx.xxx.xxx] #5.0.0 smtp; 5.1.0 - Unknown address error 572-'[email protected] host name is unknown' (delivery attempts: 0)> #SMTP#

Being fairly new to exchange and email I'm not sure why this is happening. I've verified our DNS and MX records, checked our reverse DNS entries, etc. It looks like it's being rejected from the other side but I don't know why. Google has been of surprisingly little help so hopefully a [H] expert can help me out.

Thanks
 
are the remote recipients all from the same domain? is there anything similar between which recipients work and which don't?
 
I did some more digging, apparently we had a slight mis-config on our fake MX records, once that was cleared up we were good to go (we had an address of all zeros, which wasn't RFC compliant and caused them to fail, primarily with this provider though, which was wierd).
 
Back
Top