I have two Macs, one running on 10.6 and the other on 10.7 systems. I can receive and send Exchange emails on the 10.6 (mail 4.6) computer but not from the 10.7 (Mail 5.3) computer. The Account summary and set up is the same but I can not receive or send. I checked the account activities, all green. Checked the connection doctor, all green. Deleted adn re created the email account, the server accepted, yet I am still can't receive or send emails from the computer with 10.7 system. Any suggestions.