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Can't Send Mail Through AT&T SMTP Server (on TB 102.9.0)

  • 3 replies
  • 0 have this problem
  • 1 view
  • Last reply by Toad-Hall

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I've recently migrated from POP3 to IMAP on my AT&T account, which uses sbcglobal.net in the Yahoo domain. I set up my outgoing server to be smtp.mail.yahoo.com through port 465 using SSL/TLS connection security and Oauth2 authentication, all unber Win10.

When i try to send an email, I see what looks like a browser window open up with the title "Enter credentials for my_email@sbcglobal.net on smtp.mail.yahoo.com. This window remains open only a few seconds with the a URL of

https://login.microsoftonline.com/common/oauth2/v2.0/authorize?response_type=code&client_id=9e5f94bc-e8a4-4e73-b8be-63364c29d753&redirect_uri=https%3A%2F%2Flocalhost&scope=https%3A%2F%2Foutlook.office365.com%2FIMAP.AccessAsUser.All+https%3A%2F%2Foutlook.office365.com%2FPOP.AccessAsUser.All+https%3A%2F%2Foutlook.office365.com%2FSMTP.Send+offline_access&login_hint=my_email%40sbcglobal.net

The windows them closes. If I wait long enough or cancel the send operation I see a popup that says

Send Message Error "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.mail.yahoo.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'."

My default browser is chrome and I assume a Chrome window gets opened directed towards that URL. If I open a browser window and enter the above URL, I see "This site can’t be reached localhost refused to connect" from either Chrome of Firefox. I am absolutely certain my password is correct, so what am I doing wrong?

I've recently migrated from POP3 to IMAP on my AT&T account, which uses sbcglobal.net in the Yahoo domain. I set up my outgoing server to be smtp.mail.yahoo.com through port 465 using SSL/TLS connection security and Oauth2 authentication, all unber Win10. When i try to send an email, I see what looks like a browser window open up with the title "Enter credentials for my_email@sbcglobal.net on smtp.mail.yahoo.com. This window remains open only a few seconds with the a URL of https://login.microsoftonline.com/common/oauth2/v2.0/authorize?response_type=code&client_id=9e5f94bc-e8a4-4e73-b8be-63364c29d753&redirect_uri=https%3A%2F%2Flocalhost&scope=https%3A%2F%2Foutlook.office365.com%2FIMAP.AccessAsUser.All+https%3A%2F%2Foutlook.office365.com%2FPOP.AccessAsUser.All+https%3A%2F%2Foutlook.office365.com%2FSMTP.Send+offline_access&login_hint=my_email%40sbcglobal.net The windows them closes. If I wait long enough or cancel the send operation I see a popup that says Send Message Error "Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.mail.yahoo.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'." My default browser is chrome and I assume a Chrome window gets opened directed towards that URL. If I open a browser window and enter the above URL, I see "This site can’t be reached localhost refused to connect" from either Chrome of Firefox. I am absolutely certain my password is correct, so what am I doing wrong?

All Replies (3)

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I believe ATT requires an APP password when using email clients.

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re :I've recently migrated from POP3 to IMAP

You cannot simply change the server settings of the pop account over to settings for an imap account. Can you answer a few questions and provide some info?

Did you create the IMAP account as a completely new mail account for the sbcglobal.net email address?

If you create the New > Existing Mail Account for the sbcglobal.net email address and set up as 'Imap' using the yahoo server settings, then you should have been through all the oauth set up already. Did that occur ?

What have you got set up here:

  • Menu icon > Settings > Privacy & Security

Under Passwords section click on 'Saved Passwords' click on 'Show Passwords'

You should see an oauth://account line for the @sbcglobal.net email address = user name. Do you see any other lines for that same @sbcglobal.net email address ? eg: imap://account... mailbox://account... smtp://account...

What do you see ?


Post the following information:

  • Menu icon > Help > More Troubleshooting Information
  • Under 'Mail and News Accounts' section
  • Upload an image showing all that section OR copy all the data and paste it into this forum question.

We do need to see all the accounts listed to understand whether another settings could be being used on more than one account.


Regarding the link you posted: It should not be using the link you mention because that is for Microsoft and the outlook server and not yahoo. So it is not going to work.


1. Have you got any program on your computer which is using the localhost maybe to update webpages on a website etc eg: Apache ? If yes, then you need to switch it off. Once oauth has been created then you can switch it back on.

2. Are you using a VPN ? If yes, then switch it off or create a Tunnel so that Thunderbird can use Tunnel bypassing the VPN.


3. Have you set up Thunderbird to allow cookies ? Check you have these settings:

  • Menu icon > Settings > Privacy & Security
  • Under Web Content section
  • Select checkbox 'Accept cookies from sites'
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Once you have posted info, the settings ect can be checked.

If this is not working as expected then I suggest you use a different set of server settings and also get an app specific password/secure mail key to use in Thunderbird.

  • Adjust server settings for the imap account.
  • Incoming server : imap.mail.att.net
  • Port: 993
  • Connection SEcurity: SSL/TLS
  • Authentication Method : Normal Password
  • User Name: full @sbcglobal.net email address


  • Outgoing server : smtp.mail.att.net
  • Port: 587
  • Connection SEcurity: STARTTLS
  • Authentication Method : Normal Password
  • User Name: full @sbcglobal.net email address

When prompted for password you enter the 'Secure mail key' password.