Thunderbird Community Forum

Today when trying to send an email I get Sending of message failed. The mail server responded: Mailbox full. I use an Outlook address. I have emptied my trash, spam, and sent items folders along with moving many of the contents of my folders to the Local folders.

I tried the automated setting up - several times but get the error message below, I tried changing the authentication but same result.

I tried the Help here: https://support.mozilla.org/en-US/kb/thunderbird-and-hotmail - but it didn't help!

I have the settings it shows for Outlook - but it doesn't work! When I "Continue" I get Authentication error. Show less

"Unable to log in at server. Probably wrong configuration, username or password.". It hasn't asked for a password.

I can login in to Outlook webmail and receive messages. Please help. I'm not overly technical but not totally ignorant either! Thanks, Isobel

Hello This is a Thunderbird on Windows 11 question If I select a file, right click and then click on "Send to" >"Mail Recipient", Windows tell me

There is no email program associated to perform the requested action. Please install an email program or, if one is already installed, create an association in the Default Programs control panel.

But Thunderbird is installed, up and running and is set as default for MAILTO (see image)

So what could be the problem?

Luckily, files can be loaded into messages using the "Attach" command in Thunderbird if that gives you a clue

Thanks in advance for any help

I am currently unable to send emails. I am getting a error message saying: Connection refused - OB116. 159.196.15.181 is blacklisted in Abusix Mail Intelligence. I can receive emails but not send them.

Hi

"I am being asked daily for my pop3 password

Login to server pop3.tpg.com.au with username ##### failed. retry, enter new password, cancel"

Each time I enter the password and my mail rolls through. I have the password saved using the password manager and I can see that the correct password is saved. 
What do I do to stop this happening each day? This has only been happening since the last windows update so maybe a clue there

Any assistance will be very much appreciated

I recently set up Thunderbird for Windows as a troubleshooting step for my Yahoo Mail account which has been generating an incessant number of authentication pop-ups in Microsoft Outlook (Classic) for Windows. I had been using New Outlook for many months before switching to Classic Outlook a couple of weeks ago. With New Outlook, there had been no authentication issues nor pop-ups appearing. I have been using the OAuth authentication, not app passwords, in all cases.

Setup within Thunderbird was relatively easy and the OAuth authentication went through without issues. The account has synchronized and seems to be continuing to do so as I read, delete, and send messages.

However, when I went in to the Activity Manager, I'm seeing a number of errors, appearing every 10-15 minutes or so. They read as follows:

• Alert from account xxx@yahoo.com: AUTHENTICATE Server error - Please try again later

• The current operation on 'Inbox' did not succeed. The mail server for account xxx@yahoo.com responded: UID FETCH completed.

• The current operation on 'Inbox' did not succeed. The mail server for account xxx@yahoo.com responded: p.

Can anyone help me understand what they mean? It would help me stabilize Thunderbird and might give some clues as to what is happening in Outlook Classic for me. It would seem some have authentication issues with Yahoo on different platforms while the service works perfectly fine for others. I would like to move away from Yahoo as I find it finicky with a number of its features, but I'm a long-term user (25+ years) and don't see that being a practical solution at the moment.

Thanks!

I use Thunderbird with a info@... account hosted by TransIP.

When I send an email, especially when I reply to a previous email and even more when this was my own email, the sent email is not always saved in the Sent folder: neither in the webmail of TransIP nor in Thunderbird. It seems random when emails are and are not saved in the Sent folder.

The replies are sent through; the recipient receives them.

What can I do?

The email from ALL of my other active accounts (7 or 8 of them) all download fine.

Only ONE account throws off the Unable to Write Email to the Mailbox!

I have rebooted, I have compacted folders, I have repaired the folder - same result. Only ONE of my numerous emails fails to download messages.

ALL of the email databases are in the same subdirectory that Thunderbird (obviously) has complete read/write access to.

What now???

Not sure where/how to post this, so starting here (and happy to move/amend this posting as appropriate.) 15-Oct-2026

Background: I've got a yahoo ("free") email account for many years, and wish to move the current contents of my Inbox to a folder (on imap, not local). Recently yahoo appears to have moved to "cloud" arrangement internally (not sure, but it appears to be the case.) The problem I'm experiencing (below) I believe may be yahoo's back-end cloud processes getting out of sync with Thunderbird's view of the same activity. Therefore, I'm seeking help on how to accomplish this (=I don't think there is a bug in Thunderbird, rather this is a plea for how to manage yahoo's email service for my account.)

Symptom: Moving large number of emails between folders both hosted on yahoo, peers to my inbox on yahoo, using imap - the "export" imap service). Thunderbird says it completes the task, but many (not all) of the moved emails re-appear in yahoo's inbox after a short time, so this makes moving a large (more than a few hundred) emails a *very* laborious process.

What I'm trying to do: I wish to move my current inbox (has about 7.5K messages) to an IMAP-hosted folder (same account, etc.,yahoo email would see this folder as a peer to inbox). When I select all of the messages on inbox and tell Thunderbird to move these to the local folder, thunderbird appears to indicate the task was completed. If I move a very small number of emails at a time, that does complete successfully (=thunderbird says task completed, and the moved emails do not re-appear in yahoo inbox.)

Thanks for looking at this (long) posting and (particular to moderators) if I've posted this incorrectly or in wrong place, please assist!

Dave

Despite my attempts to find an error in my outbound mail settings, I keep getting the message below.

The test of the connection to the server passes everytime, but the mail form will not allow mail to be sent.

It's the ESR version. It all started when I added a vcard to my outbound mail.

"Sending of the message failed. An error occurred while sending mail. The mail server responded: Sender refused. Please verify that your email address is correct in your account settings and try again."

When I try to send out an email, I receive an error message that states, Sending of message failed. An error occurred while sending mail. The mail server responded: <cjmst61@charternet> sender rejected. Please verify that your email address is correct in your account settings and try again. I have checked my settings and still can't send