POP3 server won't let me log in

Try these servers instead of the att.net servers

pop.mail.yahoo.com  port 995/SSL

smtp.mail.yahoo.com  port 465/SSL

@tonydi  The yahoo servers don't work for me. 

I've been using Outlook 2007 for the past 12 years on my Windows 7 machine to access both att and yahoo emails. Suddenly, about 2 days ago, Outlook refused to connect to the yahoo mail server.

My att email (strangely) is still working, but I cannot get the Yahoo account to work. I've tried every combination... POP, IMAP, different ports, different security protocols and I've generated secure mail keys 5 times. Nothing works. And it's not my Outlook install or computer. I've tried setting the account up with Outlook on a different machine, and I got the same error. 

BUT, it works fine in Thunderbird! 

Yahoo changed something that has made it incompatible with Outlook. 

I'm confused.  You are using a Secure Mail Key which is for AT&T email accounts hosted on Yahoo, but now you bring up a Yahoo account (yahoo.com) that isn't working.

Yahoo.com accounts have their own "special" passwords, called an App Password.

Thunderbird works because it has OAuth2 built in, which negates the need for any sort of special passwords.  It just uses the same password that works when you log into webmail.

@tonydi 
Apologies, I should have clarified... I'm using a secure key for my AT&T email and an App Password for my Yahoo email. 

The point I was trying to make was that I can no longer get Outlook to connect to the Yahoo mail server. Neither pop.mail.yahoo.com or imap.mail.yahoo.com will connect, and it started a couple of days ago. 

(PS - Thank you for that info about Thunderbird. That's something I did not know.)

So you've checked that all the info in Outlook for your yahoo.com account is correct, right?  Servers, port #'s, authentication types?  Outlook has a nasty habit of changing port numbers when you aren't looking.

Anyway, what's the exact error message Outlook is giving you when it fails to connect with your yahoo.com account?

I don't know about the App Password but I know that the AT&T SMK can often work just fine and then suddenly it doesn't.  Deleting the SMK and creating a new one usually does the job.

I wonder if that's also true of the Yahoo App Password.

I can't figure out why AT&T is helping you with your yahoo.com issues unless they were equally confused. 

@tonydi 
"So you've checked that all the info in Outlook for your yahoo.com account is correct, right?"

Yes. I've checked and double-checked all the settings 10 times. I've removed the account and re-added it in Outlook it on two different computers. Plus I've used all the same settings and password in Thunderbird and it works fine. 

The error I get in Outlook is something like, error (0x800CCC0E): ‘Outlook cannot establish a connection to the incoming server' 

It really makes no sense. The email was working a few days ago. Absolutely nothing changed on my system between the time it was working, and when it stopped. No updates or changes. And if it was an issue with my computer or Outlook install, it's unlikely I'd get the same error on a different computer. I'm convinced something has changed on Yahoo's end. 

"I can't figure out why AT&T is helping you with your yahoo.com issues..."

They're not. I was Google searching different terms trying to find out if anyone else anywhere is having this problem and I stumbled upon this thread.

(probably because Google spotted this text in your post...)

pop.mail.yahoo.com  port 995/SSL

smtp.mail.yahoo.com  port 465/SSL

Yes. I've checked and double-checked all the settings 10 times. I've removed the account and re-added it in Outlook it on two different computers. Plus I've used all the same settings and password in Thunderbird and it works fine.

Well then maybe you aren't using OAuth2 in Thunderbird because if you're using the Yahoo App Password instead of your regular password it wouldn't log in.

Look at your account settings in Thunderbird for the yahoo.com address.  In Server Settings and in the SMTP Server settings does it look like this....

@tonydi 
The Connection security is set to SSL/TLS and the authentication method is not selected (it's blank.)

Well that's weird.  As you can see below, there are multiple options and you'd think at least one of them would show up.  For grins I just set up a new TB installation on a virtual machine and it automatically chose OAuth2.

That being said, I guess if it's all working ok then maybe it's not worth fooling with.  😁

Back to the original problem, mine simply stopped working on August 4th after working flawlessly for 25 years.  So far, I've talked to 9 different people at AT&T and they have no clue what the problem is - they simply want to tell me how to configure Outlook or to simply keep changing the password until it decides to magically work!  Still looking for the real answer...