Can't verify AT&T Yahoo emsail account

This is driving me nuts, and AT&T is no help (They use Yahoo for email). I got a message in my Outlook email program saying that there was an error 553 and that I needed to verify my email address. I went to the account options to enter the account information, following the instructions given on this webpage:
AT&T Email- Error 553: verify your email address

I fill in the data and click verify, but I never get the confirming email it says it sends. Has anyone had a similar problem and successfully verified the account? I don't understand why this suddenly happened, since we've been using this email account for at least 10 years with no problem.

If I'm reading the directions correctly you're expecting a confirmation email at a non-ATT email account such as a Hotmail or Gmail account?

Try adding the ATT address to your alternate email account contact list and/or send an email to your ATT from that account. Developing a relationship between the addresses can help emails that might look like spam get past ISP spam filters.

The account is actually a Yahoo account. AT&T uses Yahoo as its email engine. So our incoming email server is pop.att.yahoo.com. What I can't find are a "email verification for dummies" document or help page that explains what has to go in all the slots. After inputting what I think is the right information to do the verify, I get this message (in this case for our d.doiron@snet.net) Before you can send messages from this address, you need to verify you own it. This is to protect your privacy. Step 1 Check d.doiron@snet.net for a mail from Yahoo! Member Services Step 2 Click on the link in the message