Adding work office 365 mailbox to my Yahoo mail mail issues

Hi mac1574, Thank you for reaching out to us. We understand that you're facing issue accessing your AT&T mail account. We hear you, and happy to assist you.

Furthermore, we recommend that you create a secure mail key for the mail client. It’s easy to create a secure mail key from your mobile device, tablet, or computer. Have your User ID and password ready to sign in to myAT&T.

1. Go to your myAT&T Profile. Sign in, if asked.
2. Scroll to My linked accounts, select the email account that needs a secure mail key.
3. Scroll to Secure mail key, select Manage secure mail key.
4. Choose the email address that you’d like to use, if you have more than one.
5. Select Add secure mail key. Enter a nickname for the secure mail key to make it easy to recognize.
6. Choose Create secure mail key.
7. Select Copy secure mail key to clipboard. Make a note of your secure mail key  for further updates.   
   • For security purposes, the secure mail key only displays until you select OK. 
   • If you lose or forget the secure mail key, you can always create new secure mail keys.
8. Select OK.
9. Go to your preferred email app, replace the existing password with your secure mail key. For an IMAP account, delete the existing password for both the IMAP and SMTP servers. Replace them with your secure mail key.

Good to know: Each device you use to access your email will have its own secure mail key.

Let us know how it goes.

For any further assistance we're here to assist you.

Thank you.

Rob, AT&T Community Specialist.

This doesn't help my issue. I work at Washington University and I have added my added my @wustl.edu Office 365 email address to my list of mailboxes and every few days it keeps asking me to sign-in again even thou I never signed out.

Hi @mac1574,

Thank you for reaching us. Let's get you signed back into your email by pointing you to the right direction!

After reviewing your concern and trying to resolve through the Community Forums, it looks like you may need more account specific support. To assist you best, we encourage you to review our Contact Us page to identify what method you’d prefer to reach out for this account level help.  You can call, chat, or reach out via social media, and we can review your specific issue and provide you support.  We’re sorry we weren’t able to resolve your concern directly in the forums, but let us know if we can assist with anything else.

Thank you,

Bill, AT&T Community Specialist.

This is what I have been getting every few days.

I haven't changed my password or any security settings.