txt.att.net operators

["Mike Walter" <mwalter () 3z net>]

We have been struggling to locate someone at AT&T that handles the
txt.att.net servers.  We have clients in our data center that can no
longer send emails to mobile phones via 10digit () txt att net.  We have
contacted AT&T and they say there is no problem on their end.  We can
ping the server, but simply cannot connect to port 25.  We have checked
all firewalls of each client.  Some ranges of IPs work and others don't.
Looking for someone with a clue who can assist.

Mike Walter