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Functionality and usability issue: I use the Thunderbird for Android app as an adjunct to my desktop installation. Recently I had occasion to reply to an email in Android to one "to" recipient and needed to add two "cc" recipients, but found no way to add the cc recipients without deleting the existing cc recipients and having to input the entire (dynamic) group again, but then was also stymied by that. How best to handle this issue?

Other than that issue, the lack of desktop contacts synching, and the lack of spam filtering, Thunderbird for Android has been a huge help, so thanks to the developers for their dedication and hard work.

All was well until about six months ago. When I try to connect to my provider TB won't connect. BUT. At other times it will connect then every few minutes will try to connect again - then again .... I get this message "Connection to the server mail.comcast.net timed out". Then I get this message each time it fails "Login to server mail.comcast.net with username 170834000 failed". It keeps asking me to input my password even though everything is working appropriately. Then at other times it says it doesn't connect but it has connected and it still continues to ask me for a password.

I have uninstalled TB and reinstalled it thinking that would fix it - it didn't. I have changed my password - again to no avail. I let TB choose where to put things and configure each item appropriately. I don't try to get in the way of what works.

Comcast is apparently getting out of the email business and asking everyone to move over to their chosen substitute (Yahoo.mail) and I have not chosen to migrate at this point. Maybe that's the problem. This is the message I get each time I log into Comcast.net:

"A better email experience is now available for you

You're invited to upgrade your email account to Yahoo Mail, so you can enjoy a more user-friendly experience. Your email address, messages, folders, and contacts will not change.

With Yahoo Mail, you'll enjoy enhanced security, a built-in calendar that's easy to use, AI-powered inbox organization, and a top-rated mobile app for easy access on the go."

I am not aware of any changes in the settings from before when it was working well and now when it seems to be erratic.

I am not terribly computer savvy, but I'm usually able to trouble shoot and fix the issues that confront me. This time I'm out of my league! I need help.

Thank you for helping me.

just about every other website I request a website, says no can't connect now. (obviously good reason to find another browser)

browser gives couple lame fixes.

why don't you fix it

I prefer to have the Contact Name only display in the TO: field of composed or outgoing emails. I already know their address is correct in my Address Book, why do I need to see it? Presently, the TO: field shows "Name <email address>", as shown in the first uploaded image.

I am a new user to Thunderbird and I have reviwed, and believe, set all the Settings correctly that I could find on the subject (see second uploaded image), but the results do not change.

What am I missing?

Thanks Matt T

Every five minutes Mozilla sends me a page asking for access to my Google account. I click "deny" and it goes away for a few minutes, but comes right back. And while it is on, I can neither send nor receive email. Is there some way to get it to go away and stay away? Thanks, Larry Wright

Is anyone else having problems after last update? UI too big for my laptop and most things not adjustable. Almost unusable any way to fix? Version 153.0.3 Everything is blocky like on Gmail left side too big and takes up 30% of screen. No way to adjust it.

Top of Screen where menu bar is , home screen options, Mobile Bookmarks and tabs is way to big and forces you to have to use the vertical tabs. I often work with multiple tabs and find it annoying to have to enlarge and shrink the vertical tabs when ever I want to switch tabs. Real Pain in the you know where.

I have been using firefox for many years and Love it. but if these issues persist, I might have to finally begin considering other options.

I would hate having to switch to Chrome. I dislike using that browser even thou most websites are being designed around it, which is inconvenient, but I have tried to tow the line and be loyal to my favorite opensource browser.

Please help. Any suggestions welcome.

[redacted email from community support forum] RE: Firefox Browser Help if you contact directly in subject line so I can easily find it.

I would like to set up a passkey to make logging in more convenient, but it keeps failing. My network connection is normal, and I don't have a VPN turned on. After entering the verification code, I don't do anything—I just wait for the passkey to be sent. But either it times out or says it's been cancelled, even though I haven't done anything. I've also tried using mobile data, but the same thing happens. I hope you can help me. Thank you.

I am assisting an elderly user with a personal @hotmail.com account that receives email successfully in Thunderbird but cannot send. I have confirmed they can send and receive emails from their online outlook.com portal. The user's computer setup is as follows:

• Windows 11 (with latest updates).
• Thunderbird 153.0.2 (64-bit).
• A personal @hotmail.com account with the following server configurations:

  -> Incoming IMAP: outlook.office365.com, port 993, SSL/TLS, OAuth2, and
  -> Outgoing SMTP: smtp-mail.outlook.com, port 587, STARTTLS, OAuth2.

Thunderbird successfully authenticates to Microsoft using OAuth2 for incoming email. However, when Thunderbird attempts outgoing email authentication, Microsoft's SMTP server rejects the authentication. The Error Console in Thunderbird records this message: "535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Mailbox."

-> Refer to attached image: "Thunderbird Error Console_20260811.jpg". -> I am able to provide a short screen recording demonstrating the failure if needed.

To try and resolve the above, I completed the following actions:

1. Confirmed Thunderbird is current (153.0.2).
2. Confirmed SMTP is configured for OAuth2 rather than Normal Password.
3. Confirmed port 587 and STARTTLS.
4. Re-authorised the Microsoft account/OAuth connection.
5. Confirmed IMAP OAuth2 works.
6. Confirmed Outlook.com webmail can send successfully.
7. Reviewed Mozilla's current “Microsoft OAuth Authentication and Thunderbird in 2026” guidance, including the section covering cases where IMAP/POP works but SMTP does not.
8. Captured the SMTP failure in Thunderbird's Error Console.

However nothing worked, so I raised the matter with Microsoft support and eventually had the matter referred to their Tier 2 team. The Microsoft case number is: 7107041963.

Microsoft Support confirmed that for a personal Outlook.com/Hotmail account there is no user-accessible mailbox-level SMTP AUTH setting, and advised that SMTP is enabled by default for supported clients. However, because sending from Outlook.com webmail works, Microsoft Tier 2 declined to investigate the SMTP server response further and directed me to Thunderbird support.

I am able to provide a copy of the chat transcript if needed.

In any event, the TLDR version IMAP works using OAuth2, but SMTP using OAuth2 fails because Microsoft's SMTP server reports SmtpClientAuthentication is disabled for the Mailbox. Microsoft Tier 2 has referred the issue to Thunderbird support.

Questions:

1. Is this a known current issue affecting personal Outlook.com/Hotmail accounts using Thunderbird?
2. Is 535 5.7.139 SmtpClientAuthentication is disabled for the Mailbox known to occur with Thunderbird OAuth2 even though IMAP OAuth2 succeeds?
3. Is there a current Thunderbird-side workaround or alternative SMTP server/configuration recommended for personal Hotmail accounts?
4. Would changing the SMTP server from smtp-mail.outlook.com to smtp.office365.com be appropriate for a personal Hotmail account in Thunderbird 153, or should the current Microsoft-documented server be retained?

-> I note there appears to be conflicting advice on this point in previous support threads.

1. Given that IMAP OAuth2 authentication succeeds for the same Microsoft account, does this indicate that Thunderbird's Microsoft OAuth authorisation itself is functioning correctly, or could SMTP require a separate permission/token that may be failing?
2. Are there any additional Thunderbird logs or diagnostics I can provide that would help resolve this matter?

Disclosure: I used ChatGPT to help organise my troubleshooting notes and technical details for this post. The troubleshooting, observations and diagnostic information described above are from my own work on the affected PC.

On two different Windows machines, current Firefox (153.0.1), the alt-d shortcut stops working: it does nothing until I restart Firefox. Then it works again for a while. I've tried about:keyboard and it's not reset there. I tried all combinations: Clear, Reset, setting it to alt-d explicitly. None of those worked. But when I set it to alt-a, that worked--but then resetting back to alt-d again didn't work. That shortcut is muscle memory at this point, so it's quite distressing. Not sure what diagnostics might be available to help here, happy to try anything.

Full disclosure: Both machines are Windows 10 but since that's stable, I find it hard to believe that's related.

I used to use the Google browser and within that I had a tool where I could put what looked like a sticky note on my emails and make notes like when I received the email, when I followed through on it, etc. I hear there is a tool like that for Firefox named Tags but cannot find it in my Settings. Has anyone found this and can you tell me how to access it if you have?