So on my 2007 MacBook I have 3 e-mails in the Mail app (1- MobileMe, 2 - My godaddy site e-mail @mysite.com 3- a customer service e-mail from godaddy (ie email@example.com). I can send / receive e-mails with no issues. Also on my iPhone works perfectly. I just purchased a 2011 15" MBP and configured all of my e-mail accounts. For some reason I can receive e-mails to all accounts I just can't respond unless they are from MobileMe. I have checked all server settings, IMAP settings, ports etc. Everything is the exact same as it was on my MacBook, so does anyone have any ideas why this is happening on this Mac and not my iPhone or MacBook?