Just had U-Verse installed at home and had problems sending email from Apple Mail. Receiving mail was not a problem; just sending. It worked fine with our previous provider Time Warner. Entering the SMTP server name, which was all we had to to do with Time Warner, did not work. We called AT&T and they said that they would fix it for a fee (talk about bad profits, right?).
Anyways, we finally got it to work and hopefully this helps resolve your issue. Here's what we did:
1. Log in to Yahoo! with your att.net email account that came with your AT&T subscription.
2. Once logged in, add the non-AT&T email addresses you use on Apple Mail (e.g., work email, personal mail, etc.). These additions have to be verified so check the confirmation email from U-Verse using web-based email services (e.g., mail2web.com) and click on the links.
3. Once you've added your other emails (AT&T calls these sub-accounts) to your att.net email account, go to Apple Mail on your MacBook and add your att.net email account. Just follow the onscreen instructions and Mail will set everything up, including the SMTP server name, etc.
4. Send a few test emails from your non-AT&T email accounts to check if they are going out and getting sent.
That's it. It's been a couple of days and it seems to be working fine.
By the way, if you've got an iPhone, simply add your AT&T email account (under Settings/Add Account, choose Other) and now you should be able to send/receive from your non-AT&T email accounts.
Hope this helps. If it does, spread the word. No one should have to pay AT&T for something that should easily work. The least AT&T can do is make sure the information to fix the issue is readily available and easily discoverable on their site. By the way, when we called them, they said that they could only support att.net email accounts, hence the fee. Hello?