https://support.mozilla.org/en-US/kb/password-manager-remember-delete-change-tb

Mailkeys are a direct replacement for your password in this process, so delete anything associated with the account in the password manager and enter the key (ctrl+V works if there is no right click menu for paste) when prompted.) when asked for your password and it should work, although I have a feeling generating a new key may well cancel older ones. But I really have no experience with ATT's rather contrived processes as I am not a customer.

What I do know is you can set up an ATT account in Thunderbird by using all the settings for a Yahoo mail account and simply substitute your ATT email address as the user name to access your mail. It also allows access to oAuth authentication which is actually the preferred method, just ATT never got around to doing their part in creating the Oauth environment, other that write inane support documents suggesting you use it.

I reverted some changes: I went back to port 995 and SSL/TLS. I had misread the documentation at https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202 . I kept OAuth2. Now the Error Console has these lines:

mailnews.pop3.289: Connecting to pop://inbound.att.net:995 Pop3Client.jsm:141:18 mailnews.pop3.289: Connected Pop3Client.jsm:295:18 mailnews.pop3.289: S: +OK Hello from jpop-0.1

Pop3Client.jsm:348:18 mailnews.pop3.289: C: CAPA Pop3Client.jsm:508:20 mailnews.pop3.289: S: +OK CAPA list follows

IMPLEMENTATION jpop-0.1

EXPIRE-NEVER

PIPELINING

RESP-CODES

TOP

UIDL

USER

SASL PLAIN XOAUTH2

.

Pop3Client.jsm:348:18 mailnews.pop3.289: Possible auth methods: XOAUTH2 Pop3Client.jsm:597:18 mailnews.pop3.289: Current auth method: XOAUTH2 Pop3Client.jsm:668:18 mailnews.pop3.289: C: AUTH XOAUTH2 Pop3Client.jsm:508:20 mailnews.pop3.289: S: +

Pop3Client.jsm:348:18 uncaught exception: initFromMail failed, hostname: inbound.att.net

I looked at the password URL you provided, but I am not sure what I have to change for my inbound POP3 server. Do I delete the password? Do I edit it and paste one of the Keys I had previously generated? As outbound e-mail is working fine, I prefer not to change any settings for the outbound.att.net server. Thanks.

I deleted the saved password for inbound.att.net, and I am not sure how/where to cut-and-paste one of the two Keys I had generated. The last Error Console has these lines:

mailnews.pop3.370: Connected Pop3Client.jsm:295:18 mailnews.pop3.370: S: +OK Hello from jpop-0.1

Pop3Client.jsm:348:18 mailnews.pop3.370: C: CAPA Pop3Client.jsm:508:20 mailnews.pop3.370: S: +OK CAPA list follows

IMPLEMENTATION jpop-0.1

EXPIRE-NEVER

PIPELINING

RESP-CODES

TOP

UIDL

USER

SASL PLAIN XOAUTH2

.

Pop3Client.jsm:348:18 mailnews.pop3.370: Possible auth methods: XOAUTH2 Pop3Client.jsm:597:18 mailnews.pop3.370: Current auth method: XOAUTH2 Pop3Client.jsm:668:18 mailnews.pop3.370: C: AUTH XOAUTH2 Pop3Client.jsm:508:20 mailnews.pop3.370: S: +

Pop3Client.jsm:348:18 uncaught exception: initFromMail failed, hostname: inbound.att.net mailnews.pop3.370: NetworkTimeoutError: a Network error occurred Pop3Client.jsm:369:18 mailnews.pop3.370: Connection closed. Pop3Client.jsm:395:18 mailnews.pop3.370: SecurityError info: Pop3Client.jsm:375:20 mailnews.pop3.370: Done with status=2152398862 Pop3Client.jsm:1486:18 Error in parsing value for ‘width’. Declaration dropped.

I solved the problem (with the assistance of Gene Smith) by generating a new Mailkey and using it as a "normal" password. I had assumed that Mailkeys were used only with OAuth2 authentication. I had not tried one of my two 2020-generated Mailkeys as a "normal" password.

Another problem was at&t phone support(Online chat connects to some AI machine that only has canned answers). I was on the pho0ne for one hour earlier this week, and the techs would not acknowledge a problem. As I could read e-mail via the web, there was NO e-mail problem. And the techs would not acknowledge that inbound.att.net is an at&t mail server.

I solved the problem (with the assistance of Gene Smith) by generating a new Mailkey and using it as a "normal" password. I had assumed that Mailkeys were used only with OAuth2 authentication. I had not tried one of my two 2020-generated Mailkeys as a "normal" password.

Back in my first post I told you mailkeys were a direct replacement for your password. Perhaps you missed it. https://support.mozilla.org/en-US/questions/1450241#answer-1657971

Another problem was at&t phone support(Online chat connects to some AI machine that only has canned answers). I was on the pho0ne for one hour earlier this week, and the techs would not acknowledge a problem. As I could read e-mail via the web, there was NO e-mail problem.

That is actually included in their terms of service. You pay them essentially for very little that they actually guarantee.

2.2.3 Data Service: If your rate plan includes data, subject to the limitations in this Agreement, you will be able to browse the internet and access wireless services, content and apps, including those that enable sending and receiving of emails, use of GPS navigation, streaming of video, and other customary mobile internet-enabled capabilities (“Data Service”). Services provided via the Data Service may be provided by AT&T or its affiliates, assignees, successors, or by third parties subject to service-specific terms and conditions.

No mention of how you get the service, just that you do. Webmail is their definition of delivering that service.

There is a lot of marketing guff but little substance to their support. But that does not necessarily mean it is an AI. They have employed script readers to answer their support phones for decades that I know of. If they have replaced them with a brain dead AI, I would see that as no real change. The support was only ever any good at taking your credit card or upgrading your service.

And the techs would not acknowledge that inbound.att.net is an at&t mail server.

It is not, it resolves to any-jpop.mail.gm0.yahoodns.net

That is it is a yahoo server and mail is actually a service offered under contract to ATT by Yahoo and has been for a long time now. By default ATT really know nothing about their mail offering because they do not supply it, only offer links to it. Yahoo offer no support because their contract does not include that.

What I do think is you should really set up your account in Thunderbird as a Yahoo one with settings for the relevant Yahoo mail account type. IMAP, POP or SMTP and simply substitute your ATT email address as the user name. This allows access to Yahoos preferred authentication method of oAuth. Something ATT have suggested folk use, but have failed to undertake their end of the process to allow for years. Their support documents even blame those that can not use it for their failure to complete the server side requirement of having a client secret to use.

I suggest this because dealing with the vagaries of Yahoo is hard enough, without doing it through the filter of ATT.

Thanks for the reply.