I've read most of the posts about Mac Mail issues, but none are quite like this. Like the others, my Mac Mail will receive, but not send, messages. Four accounts are on Verizon, two on GoDaddy. Web mail works on all, Blackberry email works. Mac Mail does not. I have talked to Verizon (my ISP), taken my Mini to a Mac repair shop -- even installed a new (bigger) hard drive. I'm using Leopard, OS 10.5.8. I've tried setting authentication on. I've tried turning authentication off. Every once in a while, one or two messages in the outbox will suddenly send, while the rest of the messages don't go anywhere. At the repair shop, the tech worked most of the day before getting them to send (one test message from each account), declared the computer fixed and sent it home. Once it was home and plugged in again, I was able to send one test email before it quit sending again. Needless to say, this is very frustrating. Thanks for your suggestions!