Thunderbird Community Forum

I've done EVERYTHING.

New install of latest version. edited profile to point to saved data on USB external drive DELETED every instance of lock files terminated task numerous times. rebooted 3 times...

What now???

I am using Thunderbird Meadow.

Is it possible to send emails without a subject, other than getting the warning dialogue box.

It would be very useful.

Thank you

I updated t the latest version of Thunderbird but since then none of my email addresses were changed with the update. Tried all the advice on line but still can't retrieve my saved email addresses from the inbox and sent box

For a few weeks now, sent emails have not been appearing in the "Sent" folder. The recipient receives the email, but I have no confirmation in "Sent" that it was actually sent. It was never a problem.

My Thunderbird email account no longer lets me send out messages. I get a message error

  QUOTE____

Sending of message failed. An error occurred while sending mail. The mail server has responded. Message contains bare CR and is violating 822.bis section 2.3. Please check the message and try again.

But I am able to receive messages.

Can anyone help. Thanks in advance!!

bob.fannon

Feb 14, 2026, 13:01 CST

I have used Thunderbird for a number of years with Plusnet (using POP settings) in the UK. However, Plusnet has transferred their support to a company called Greenby who have made a hash of it and offer very poor support. So, I want to use Outlook as the mail server but I am unable to send any messages via Thunderbird to the Outlook server. I can however download messages with no problems. The error message I get is :- Sending of the message failed. Unable to authenticate to Outgoing server (SMTP) smtp.office365.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'

My default Outgoing Sever settings are :- Server Name : smtp.office365.com Port: 587 User Name: bob.fannon@outlook.com Authentication method: OAuth2 Connection Security: STARTTLS

I have tried deleting the Thunderbird account and re-creating it but still got the same result. I also tried to use my old Icloud account ( having first setup my App Specific password) but got the same result.

We are facing issues with Thunderbird mail application.

Incoming emails are not being received in Thunderbird. Thunderbird is running very slowly and frequently becomes unresponsive. Sending and receiving emails is taking a long time. We have already restarted the application and system, but the issue still persists.

Kindly check the mail server settings and Thunderbird configuration from your end and advise on the necessary action to resolve this issue as soon as possible.

Your prompt support will be highly appreciated.

We're planning to switch from Outlook to Thunderbird, but we have a hard time in harmonizing font sizes on text and signature. One of the issues is that fonts can be set to textual values tiny, small, medium, etc. w/o knowing what it corresponds to in pt. But lets explain what we tried so far: - Under Settings/ General / Language&Fonts, we defined Calibri 12 as default, what we repeated under Advanced for 'Latin' & 'Other Writing Fonts' - Under Settings / Composition, we defined Calibri / Medium for the HTML Style - The HTML-signature is defined using the Calibri 12 font But when creating a new message w/ these settings, the result is terrible as you can see in the example: disregard the fonts' color, just look at the font sizes.

Is there any simple solution?

I am in the midst of the long process of moving most (not all!) of my gmail from the gmail server to TBird, using filters as discussed in this thread.

I've started by first using filters on less important emails (ie so that no true disaster occurs if something goes horribly wrong). As I do so, I have questions!

For example, let's say I use a filter to: copy all the emails from @someone.org to a local folder then delete those emails (from the server)

What happens if one of those emails happens to be within a thread, including emails from people who don't match the filter (ie are not @someone.org). Have I broken the thread forever, ie, has something gone horribly wrong? If so, how do I prevent this behavior/have the entire thread move along with the targeted value? If not, I don't see how I can move email without breaking threads, which is a bit of a problem.

(Also - whoops, I see I should update, but the question remains.)

I am encountering a message of "The installation seems to be incomplete. Please check your hardware and disk setup and/or re-install." when trying to run Thunderbird.

This first occurred on a system that had been working for a while. An update may have been installed.

Here's what I've tried. -

Uninstall Thunderbird (along with Firefox and Mozilla Maintenance.) Checked for Program Files/Mozilla folder (all were removed). Run SFC / Scannow Run CHKDSK Installed pending Windows update. Restarted the System Renamed (essentially removed) Profiles folder Turned antivirus software off Downloaded and installed the latest version of Firefox, then Thunderbird. Launched Thunderbird. Still received the same error..

Any ideas on how to resolve the issue?

All my read emails are showing on the top bar of my thunderbird. I have to scroll left past multipee tabs to get to my inbox. This just started recently and at the same time email replies started showing up under the original. can I turn these features off.

I've just recently (over the past 10 days) been notified about 3-4 times a day by Windows Defender which flagged "something" as Trojan:HTML/ScrInject.AW!MTB in "file" %temp%/newmsg.

That's where my copy of Tbird puts temp files. Closing it stops this behavior. Uninstalling and reinstalling w/out deleting my profile caused the same behavior, but uninstalling and cleaning out my profile files seems to have stopped this behavior.

I only have one extension, Compact Headers, and that doesn't seem to be the problem. Has anyone else experienced anything like this?

Jim