KINDLY NOTE THAT this article is out of date and UVerse and Yahoo apparently finally fixed their lousy stuff. Glad it was usefull while it was.
The masterminds at AT&T U-Verse have gone to a great deal of time and expense to provide their valued customers with comprehensively incorrect information regarding how to send a non-ATT.NET email through the SMTP provided at smtp.att.yahoo.com. If you use your own email address such as email@example.com and have landed here, you are not insane, even though you probably want to bang your head against the wall at this point. You have just been supplied with remarkably bad information by your new U-Verse support.
Here is the fancy version of the incorrect information regarding sending your emails though smtp.att.yahoo.com. Here is the more pedestrian and also completely useless instruction page for sending through smtp.att.yahoo.com. The useless information I am linking to is for Outlook Express. For incorrect information regarding other email agents, find the link for "personalize your support".
If you call U-Verse support on the phone, they can not help you because they don't know how to set it up themselves. If you are reading this in the India U-Verse support basement and want to actually help the clueless and deeply frustrated individual on the phone who you are trying desperately to make go away, please read the following to them, word for word:
Here is actually how do it:
Go to: http://att.net
You will land on the unholy marriage portal of Yahoo! and AT&T.
In the top right, look for "Hi, please sign in" (this will probably change soon because it is so vague and absurd, so if it's not there look for some way to log in). Click those login words.
Your user name is the email address you gave yourself at ATT.NET when the friendly person came to install your U-Verse equipement. Your password is the password you assigned to that ATT.NET email address. If you do not know this crucial information, you are most-likely without hope at this point and should probably just forget about it and give up.
After logging in, do not click on the MAIL button because that would be WAY too obvious.
Instead, click on Member Center (as of January 2013, this link has been moved under the MORE button up top, to make this process even more confounding).
Then, because this thing really is just awful, log in again! Same credentials as before.
Now, under the "Contact Information" area on the left, click on "Update Contact Information".
You will see your ATT.NET email address on that page and a tiny little link under that for Add Email. Click that.
Add your actual email addresses in there.(me@mybusiness for example).
Note that if your email address starts with "admin" such as firstname.lastname@example.org, then Yahoo! and AT&T will reject it. I have spent three hours on the phone with them trying to correct this error on their part with no result. It would take any decent programmer about 20 seconds to correct this pitiful error-checking mistake on their part. More evidence that this thing really is remarkably terrible.
Check your email and confirm it through their ugly but effective confirmation email thing.
After confirming your email address, you can now add that email address to the outgoing authentication in your mail agent program (Outlook, IMail..whatever). All the other information that U-Verse supplies after this is correct, including secure port numbers (465 for outgoing SMTP port). However - you need to use your own ATT.NET email address and password for the secure STMP login.
Oh, one more thing...AT&T instructs you to use outbound.att.net for your SMTP settings. Remarkably, this is incorrect. Instead, use: smtp.att.yahoo.com
If you work for AT&T U-Verse and are reading this and have finally corrected your bogus instructions, please post a reply stating: I'm sorry I wasted all of your time trying to figure this out and we really are a miserable service.
If you found this to be helpful, tell me. If anything I said is wrong, tell me. The internets are chocked full of bad information and I don't want this to part of the problem.