Bolt! Ya Nugget wrote:
Does anyone know why my iMac Mail won't send mail? It will receive mail and answer mail but I can't make new messages and have to use my webmail accounts. When I first got it I had a work email account which worked perfectly. Since I got rid of it and put on two new accounts, neither will send new emails.
When I got my new iMac last Xmas, it had the same problem, but I had Applecare on it, so a quick phone call to Apple support got the mail app playing nicely again. I since learned that Mail has had some long-term problems going back at least until Lion (10.7).
Have you upgraded to Mavericks (10.9) yet? I've had a new Mail update drop to (I have my MAS system updates/Apple apps set to auto-update so it just applied the patch - dated November 8th). It was primarily set to fix problems with Gmail, but some other fixes are in there as well.
It may fix your problem.