[Mailman-Users] Unrouteable mail domain errors

[Matthew Poe]

Hey all,
 
I've just moved to a new web host. A big part of the reason I moved was
so I could have access to Mailman again-I'm very happy with the cpanel
mailman integration. However, since I've been at the new host, I get an
enormous number of bounced messages. They all look like this:
 
This message was created automatically by mail delivery software (Exim).
 
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
 
  xxxxxxxx at mix.wvu.edu
    unrouteable mail domain "mix.wvu.edu"
 
Now the funny thing about them is that they're completely inconsistent.
Some list members @hotmail.com will receive a list message successfully,
while others will bounce. Ditto for yahoo, wvu.edu, and so forth.
 
I have mailman set to disable subscriptions after three bounces, and
over the past week, every time an email has gone out over the list,
anywhere from 4 list members to half of the 150 or so list members get
disabled. The web host says he's checked things out on his end, and
everything looks good.
 
I've used mailman before with these addresses from another web host's
server and not had this problem. Doing a quick google search for the
error message reveals lots of hits, but I've been unable to find any
useful advice or explanations for what's going on here. If anyone on the
list can help, I would be greatly appreciative.
 
Thanks,
 
Matthew