Thunderbird Community Forum

I have version 153.02esr. Since two days ago I cannot reply or forward messages. It pulls up the appropriate page but there is no box to send, the space is just blank in the upper left hand corner.

Hello,

My email provider is Thunderbird for my professional email address and I use Gmail everyday for receiving and sending my professional messages. However, Gmail will no longer support checking emails from third-party accounts through POP from my PC.

The option to 'Check emails from other accounts' will no longer be available in Gmail on computer. The solution that Google proposes is to set up automatic forwarding (web): To get new emails to appear automatically in my main Gmail inbox (like with POP fetching), set up automatic forwarding with your other email provider (Thunderbird). 

Can you help me with the different steps  in both Thunderbird and Gmail settings to make it work? Alternatively, is there another way to still have access to my professional emails through Gmail? Maybe through Gmail app for computer that uses IMAP instead?

For your information: My Thunderbird server settings shows:  Server type: POP Mail Server Server name: pop3.mycompany.com Username: xxx@mycompany.com (my professional email address) Port 995 Thunderbird has been updated and is currently running on version 153.0.3. My computer is running on Windows 10

Thanks so much!

After returning from a 6 day vacation, my wife attempted to download email from her Yahoo email account. There are nearly 200 messages that have piled up but they aren't moving. I've uninstalled and re-installed TB. I've uninstalled and reinstalled the app password in Yahoo. There is no problem with accessing the email via any web browser. I spent 49 minutes on a tech support call with Yahoo and they have said the problem is with TB because they repeated the same steps I have. I checked firewall settings and the only antivirus program on the computer is Malware Bytes and it's not running in the background. The version of TB is the most recent as of yesterday. I don't see any sketchy looking emails in the web version of Yahoo Mail when it's opened. It's set up as a POP3 account and has been since Cox Internet gave their email over to Yahoo. I'd appreciate any assistance in resolving this because it's currently above my pay grade and tech support at Yahoo.

Orange obliged me to have a new password to have an access to my mails , sending and receiving . But it does not work , and now I can only use Orange .What can I do ?

Coming from https://support.mozilla.org/en-US/kb/cannot-send-messages, and https://support.mozilla.org/en-US/questions/1596545#answer-1837376 (thank you christ1)

Account settings attached. I don't have an active firewall. My email provider is microsoft (outlook) No antivirus installed Linux Mint 22.3 x86_64 Thunderbird 153.0esr

I have confirmed with microsoft support that the ports and such are correct, they claim thunderbird is the problem.

Hello,

I have been using Thunderbird for years without issue, but three days ago, I started having issues.

Now, I don't receive emails when I open Thunderbird. If I delete my password and re-sign in, I receive emails, but cannot send them. Trying to send an email makes Thunderbird ask me to sign in again.

I have two email accounts that I use with Thunderbird. Both accounts have this issue. I have this issue regardless of the network I'm in (work, cell hotspot, or home).

Things I have tried:

• Verified that my IMAP and SMTP settings match the guidance from email servers.
• Verified that my computer firewall is not blocking email.
• Tried connecting on different networks (so different ISPs)
• Deleted and re-entered passwords for each account

Here my current server configuration:

• Email 1 (@gmail.com)

 * Server Name: imap.gmail.com
 * Port: 993
 * Connection Security: SSL/TLS
 * Authentication Method: OAuth2

• Email 1 Outgoing Server:

 * Server Name: smpt.gmail.com
 * Port: 465
 * Authentication Method: OAuth2
 * Connection Security SSL/TLS

• Email 2 (@[university].edu)

 * Server Name: outlook.office365.com
 * Port: 993
 * Connection Security: SSL/TLS
 * Authentication Method: OAuth2

• Email 2 Outgoing Server:

 * Server Name: smtp.office365.com
 * Port: 587
 * Authentication Method: OAuth2
 * Connection Security SSL/TLS

I will greatly appreciate any help you can provide!

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.

Im looking for help to set up my Hotmail account. I have 4 emails. They all worked perfectly for a long time. All of a sudden, everything just stopped. I have tried everything and the configuration seems to be correct. Ive tried every fix i could find. It just no longer makes sense to me. Does it just not work with Thunderbird? The specific message is "User is authenticated but not connected". Also when i tried to send an email, i get "Login to server smtp-mail.outlook.com with username **********@hotmail.com failed."

My email account [redacted from public] @live.co.uk was receiving mail until 6th August and then nothing. I'm getting a notification to say authentication failed and when I tap it the screen says "checking incoming server settings" and doesn't complete. I'm in the process of changing Web account logins from a talktalk account to the live account as the TT account is attracting spam. Could this have influenced the server settings?

Richard

Sending of the message failed. An error occurred while sending mail. The mail server responded: <support+idMM51X2-RWD3K@dealerbuilt.zendesk.com>: Relay access denied. Please check the message recipient "support+idMM51X2-RWD3K@dealerbuilt.zendesk.com" and try again.

the above is the error code. I have triple checked emails, even tried sending a message to my personal email as a test and nothing.

Hello, I use Thunderbird to retrieve my AOL mail. Starting today, when I start Thunderbird it retrieves the AOL mail and then after a couple minutes I get the attached popup. I am not trying to connect Thunderbird to any Google account and I don't understand why I would get a message saying to use Google to sing in to Thunderbird. Once this popup occurs Thunderbird will not connect to AOL until I close it and restart it. I do have GMail set to forward messages my AOL address but this screen has not come up before

Any thoughts?

Thanks, John