iphone not connecting to exchange via 3g

we allowed our domain name to lapse with Network Solutions  registrar.

as a result all of our dns records (on file with telepacific.com) ended up
on the 208.91.197.x network...
Email, websites and so on stopped working

wednesday at 6pm we resolved our problems with Network Solutions..
gradually, email is being received again from most email servers.

however... I-phones cannot connect to our Exchange 2003 server thru 3g .
They are on an at&t plan.

when i do an
nslookup and point to a server that should be the main att dns server for at&t
(which i got form doing a google search of "at&t dns servers)
  the responses for our records appear to be correct

nslookup
server 68.94.156.1
set type=A
mailmx.ourdomain.com

the response--is correct

Can anyone help solve the i-phone problem: "Cannot get mail ..connection to server failed"