The environment has 1 front end OWA/Activesync server and a 1 back end mailbox server where all the mailboxes are located. I have checked the Exchange Features of the accounts that can't connect and they are set identically allowing access at the account level. I have gone as far as copying an account that can access Activesync to a test account name and then trying to connect with the test account with no luck.
I know Activesync is up and running as several accounts are able to sync up without a problem on various mobile devices. The SSL certificate is valid and we have no problems with any accounts accessing their email via Outlook Web Access.
If I create a new account I get the same results. If anyone has seen this problem before or if anyone has any suggestions as to what steps I should take to troubleshoot, I would highly appreciate it.