The Windows Mail issue is a known one, has been for a month now.  Microsoft pushed out an update on 6/2 and shortly thereafter two problems surfaced that only seem to affect Yahoo (and AOL since they're on the same servers).  One, some emails did not display properly, looking more like raw code than regular text.  And two, Mail doesn't seem to be able to sync correctly, often times only pulling down a couple of emails even though there are many more in the Inbox.

Here's the first thread I ran across at Microsoft that discussed it.  There are more on their forums and on Reddit and other forums.

There are also issues if you delete the account in Mail and try to add it back.  At this point your only solution is to use a different client.  I recommend Thunderbird as it supports OAuth2 natively.  That's required if you don't want to have to create a Special Mail Key at AT&T.  If you're interest in doing that, I'll post a link to instructions.

As far as your other devices, yes, because they use apps and don't log into the email the same way, they haven't been affected.

I've been having the issue with my sbcglobal account occasionally signing itself out, and have had the thing where I have to reset my password because it claims I tried signing in too many times.  Sometimes what seemed to trigger it was to click on some folder besides my inbox (although that may simply be because it signed me out previous to me clicking on the folder, that action just caused the page to refresh).  However, today, a new thing has happened where it seems every couple of minutes, sometimes in the midst of reading or writing an email, other times while I'm on a completely separate window, I'll get a pop up box saying "Leave Site?" and I have to hit "cancel" instead of "Leave" or it'll immediately log me out.  This seems to happen also with EVERY click on the email page, whether it's checking a folder, following a link in an email, 'compose,' or if I look at another window, as soon as I return, I'm asked to approve the leave choice.

I haven't seen that particular pop up mentioned although we've got tons of people reporting getting bounced out, sometimes even in the middle of composing an email. 

So now we have the pop up to add to the never ending list of Yahoo oddities.  Lovely. 🙄

I was logged out 4 times yesterday from Currently.com on my laptop.  I immediately logged out from my AT&T cell phone as well, deleted the cache, and logged back again.  So far today, I have experienced being logged out 3 times and it is only 2:30 EDT!

Also, I have had the same experience with multiple browsers and my Wife is experiencing the same issues.

DirecTv used to be good with customer support and service until AT&T got involved.

@jaw1254  You're experiencing the same behavior many of users have been having for a month or more off and on.  It's odd that it doesn't happen to all users at the same time, but seems to be a rolling problem for inexplicable reasons.  Mine was doing the same thing--logging me off of webmail hourly on the PC, but using email client on mobile device not affected.  But I didn't have the other problem many people complained about getting locked out of their account repeatedly because of too many attempted login attempts.  I did change my password after experiencing the time out issue for a couple of weeks and not sure if that resolved it or was just a coincidence, but mine has worked fine now for a couple of weeks.  Good luck.  Not much you can do other than maybe change your password because none of the other generic fix-it steps that ATT suggests users try will resolve the issue which admittedly is their problem.    

My email has been working fine for the past few weeks as long as I stay logged in, but they must have turned off the spam filter because I'm getting a ton of it!

You've got that right on the lack of spam filtering!  My wife and I are both getting the (Edited per community guidelines) and Norton and McAfee renewals multiple times per day.  By the way, I did not use profanity for the Administrative edit.  I am well above that level.  The comment was regarding Paraquat and Camp Lejeune's legal matter emails.

@DeadEye57 Same here. (Knock on wood!)  The spam emails getting thru to my inbox has increased greatly since this whole thing began. At the same time, they have been showing a pop up, encouraging you to sign up for a paid subscription to their Plus email service.  Fat chance. It really does seem like they want us to either change email services or pay for their service. ?? 

I get the same popup for Plus and I'm not one of the unfortunate customers getting the spam flood.

Plus won't change the spam flood as evidenced by multiple people on these forums who thought that, paid the $5 and saw no difference.

Yahoo borked their server-side spam filter and somehow either doesn't realize it or can't figure out how to fix it.

Now it doesn't give me the option to block the spam email addresses, I have to enter them manually.  I've probably had this email address for 25+ yrs.  I hate to change but it looks like its time.