Resolved Can't send email

I've been trying since 5:00A.M. to send emails but I continue to get a message that -The message could not be sent because the connection to SMTP server smtp server smtp.att.yahoo.com was lost in the middle of the transaction. Try again or connect your network administrator.-

I rebooted my PC, tried a zillion times and then called ATT support. They verified my settings are correct and then said they don't support Thunderbird and I should "Google" for a solution.

I shut TB down and left for a couple of hours. Tried again and same old thing.
Now after that message I get one that says my password is incorrect.

Since I can access my email from the web site, the tech said it HAS to be TB.

TB was functioning last night but one thing different is I forgot to shut it down for the night. Don't know what that would do with anything but should I re-install TB? If so should I uninstall what I have now?

 

Took advice from ATT tech and tried Windows Mail (Vista)

Still can't send.

 

Update!

I was checking things out and all of a sudden my emails were going out.

I don't think AT&T knew what they were talking about. They said it showed there were NO problems with their servers but there certainly must have been.

In my opinion it was NOT Thunderbird.

Sorry for bothering everyone.

 

In my opinion, although the thread appears to be solved, there was no understanding of the situation. But, this is so typical of certain ISP, who are totally ignorant of non-Microsoft programs. How can they say that there is problem with their servers, if they don't have a clue about the programs!