This happens to me when our T1 goes down.

Close out of Mail, ascertain things are up and running, and then restart.

Does your ISP have a POP before SMTP setting (i.e., do you have to check e-mail before you can send)? Some ISP's do this to prevent spamming. Mine does. It made me really mad until I was able to set my mailer programs right.

It is a POP account. Though i have never noticed if i had to check mail first, do you mean I actually have to click on the mail "to check" because i get alot of junk and just delete such mails. This is all just on my laptop so I am not connected to a server, when I connect to the internet I open mail it checks for new mails from an account I have with an email provider and some mails I hit reply, type my message and that error appears.

that can work too, I think. I set something somewhere in mail to always do this automatically. I don't remember what it was, because by the time I found it, I had searched for ever, and was so beat,