Thunderbird crashing when sending mail from my lineone.net account

[argchichester]

My email has been working fine and I haven't made any changes to my accounts for a long time.

Yesterday, however (4th August 2025) my lineone.net account is causing Thunderbird to crash (and in fact locks out the whole system).

If I send a message it appears to be sending ok, but then I get an error message saying "Your message was sent but a copy was not placed in your sent folder (sent) due to network or file access errors".

Thunderbird then crashes both itself and the whole system and I have to do a hard reboot to get the system up again.

The email is actually being sent but not being placed in the sent folder.

My tiscali.co.uk account is working correctly through Thunderbird without issue.

I have tried sending directly from web mail which is also working correctly.

I have reloaded Thunderbird with the same results.

I have also run a system restore from about a week ago but no difference.

As mentioned, I have not made any changes at all to my settings and this problem has only arisen over the past 2 days.

Any help would be very much appreciated!

[sabelo-TT]

@argchichester, pleasure 🙂 

[argchichester]

@nameunknown_  Thank you for your message and suggestions, much appreciaqted.

Apologies for my late reply, unfortunately I had to go away for a few days.

At the moment, I can read new lineone.net mail without issue and send via my tiscali.co.uk account (both via Thunderbird).

I am apprehensive about doing too much right now in case I make the issue worse. It is rather like Russian Roulette every time I hit the lineone.net 'send' button and I really don't want to load any more image backups unless absolutely necessary.

I have written to TalkTalk who have responded and tell me they will do a full investigation into the problem. Perhaps that will be productive.

I will have a careful read through of your suggestions and have a good think about what to do next.

Thanks again,

Regards Tony

[nameunknown_]

@argchichester 

With only 13 emails in your sent folder, you would not expect file size to be an issue.  However, be aware that the Sent file contains a copy of emails that have been in the Sent folder previously and subsequently moved/deleted too. Also, there might be an issue with the index file (the .msf file).

The simplest way to rule out any issues would be to

copy the emails in the Thunderbird Sent folder to a folder under Local Folders
close Thunderbird
log in to webmail, move any emails in the Sent folder to another folder
delete the Sent file and Sent.msf file in the email account folder in your Thunderbird profile

path to the folder is of this format;
C:\Users\<username here>\AppData\Roaming\Thunderbird\Profiles\<profile folder name here>\ImapMail\<email account folder here>

Hopefully, at this point you can send emails without Thunderbird and Windows crashing. If so, you could then try moving emails back into the Sent folder in webmail (possibly one at a time), run Get Messages in Thunderbird to update the Sent Folder, and confirm whether you can still successfully send a new email.

If it's still crashing, then there's some further head scratching to be done.

[argchichester]

Thank you for your comprehensive message @nameunknown_  I promise not to bite you again.

I have now crashed my system more than 20 times with 3 catastrophic data corruptions on my C: drive (due to incomplete Windows shut downs) making my system unbootable.  Fortunately I take regular full image backups so I am able to restore the drive, but it takes about 4 hours each time and my system is locked out for the duration of the restore. That's more than 12 hours and my patience does grow a bit thin.

If I was aware of the issue causing the problem I could, hopefully,  do something to rectify that. Not knowing is worse. I am now almost afraid to use my email (after 7 days of this error occuring). If I had, somehow, caused this by something I have done, I could accept that. But I have not made any changes my system which suddenly failed on, or immediately after the 4th August.

I suppose I could set up MS Outlook and try that, but I have always preferred Thunderbird (which I have used for many, many years without issue).

I will sleep on it I guess.

Thanks again for your input. Regards Tony

P.S. Only 13 small emails in my sent folder.

[argchichester]

@angelique-TT 

Thank you.

[angelique-TT]

Good afternoon @nameunknown_. Thank you for your advice on this. @argchichester we're really sorry that you feel this way, we have sent you a PM with further details regarding putting through a complaint. 

[nameunknown_]

@argchichester 

Okay, a few days have passed. Hopefully you are not still in the frame of mind to 'bite the hand that feeds you'.

The absence of server settings in webmail Account settings is likely unrelated to the issue you have with Thunderbird crashing. (There are no server settings in webmail Account settings for any of my @talktalk.net email accounts.)

I see that you have enquired about your lineone email account being reset. I do not know whether a reset can be applied, but via the Mailbox Manager you can deactivate and activate your account. Another Community user discovered that this resolved not being able to access their email account other than via webmail, i.e. using an email application. I am not confident deactivating and reactivating the account would make any difference in your case.

You can access the email account using webmail, so it is difficult to think of what issue there might be with the server setup that would cause the issue you are seeing with Thunderbird.

You may feel that you have eliminated the possibility of the issue being caused by Thunderbird, but you may have overlooked a possible cause.

The restore that you did may eliminate the possibility of the issue being due to settings, however it does not completely eliminate the possibility that Thunderbird is causing the issue. When you opened Thunderbird after restoring the drive, it resynchronised with the email server and updated the index files (.msf files) and mail files, putting them back to the same state as when the issue first occurred. It's possible that an issue with either the Sent index file or the Sent mail file is causing the error with saving the next email you send, and causing Thunderbird to crash. It may be, for example, that the size of the Thunderbird Sent mail file has become very large.

Whilst I cannot be 100% certain the issue is with Thunderbird, I think you have to be open to the idea it is a possibility. If you are, then there are things you could investigate.

[argchichester]

Also noted @amahle-TT 

But unacceptable, rude and offensive. I pay Talktalk to use their system and it is up to me which email client I chose to use.

Thunderbird has been working perfectly for years without any issues

There is clearly some corruption on my lineone.net account.

I will be making a serious and fomal complaint regarding this issue and total lack of useful support provided.

This is the most egregious user support I have ever experienced.

[amahle-TT]

Noted, but it is not within Talk Talk scope as your webmail is working, please do use webmail as advised thanks.

[argchichester]

@amahle-TT 

Settings fo both accounts are identical and correct. (And were working perfectly until 5th August).

Tony

[amahle-TT]

The difference in functionality between your tiscali.co.uk and lineone.net email accounts in Thunderbird could be due to several factors. Here’s a breakdown of potential reasons for the issue:

It could be server settings:

Ensure that the incoming (IMAP/POP3) and outgoing (SMTP) server settings for your lineone.net account are correctly configured. Compare them with the settings for your tiscali.co.uk account

Common settings to check include:

Incoming server address

Port numbers (usually 993 for IMAP with SSL, 995 for POP3 with SSL)

Outgoing server address

Authentication methods and so on. 

[argchichester]

OK thank you. @amahle-TT 

Could you please explain to me why my tiscali.co.uk is working perfectly via Thunderbird, yet my lineone.net mail is crashing.

I just don't understand why one works and the other fails.

Tony

[amahle-TT]

Please do trouble shoot with thunderbird as webmail is working correctly, should webmail give you issues please do let us and we will be able to assist, thanks.

[argchichester]

Thank you for getting back to me so quickly on this @amahle-TT 

I really appreciate your help with this problem. To let you know my progress here :

I have uninstalled Thunderbird, deleted the profiles and removed every Thunderbird entry in the registry. I have then run a full install with the latest version.

This worked for the 1st email I tried to send, however subsequent emails caused exactly the same error as before.

When Thunderbird crashes it also crashes the whole system requiring a hard reboot.  About 30 times over the past week. This has caused corruption on my C: drive twice requiring a full rebuild from image files. (About 4 hours each time) just to get my system to boot again. It is like a time bomb.

I had a web chat with Thunderbird support who insist that this problem is due to a file access error so I am at a loss now.

Is it possible that the problem with not displaying my lineone.net server settings is related to this? Some kind of security issue on Talktalk servers?

As mentioned previously, everything was working correctly on the 4th August and I have not made any changes at all to settings in Thunderbird or Web mail. Were any changes made to the system by Talktalk after this date?

I do thank you for your assistance, as always. I just need my email to work as it did before this issue. It is 5 days now since the problem started. Web mail is ok for now but not always convenient to use.

Thanks again,

Regards Tony

[amahle-TT]

I am one of the Talk Talk Technical agents, and I would advise you to continue with webmail if the below steps do not help.

You will start by restarting thunderbird

Restart Thunderbird: Close and reopen the application to see if the issues persist.

Safe Mode: Start Thunderbird in Safe Mode to disable extensions and see if the problem continues.

Check for Updates: Ensure that Thunderbird is updated to the latest version, as updates often fix bugs and improve stability.

Create a New Profile: If the problem persists, consider creating a new Thunderbird profile to see if that resolves the issues.

[argchichester]

@amahle-TT This is happening when I try to use the settings option in web mail. (Settings/accounts/manage your accounts).

Thanks Tony

[argchichester]

Thank you for your message @amahle-TT 

The delete option is greyed out and not available, also this is my primary email account (the one I have been having trouble with for 5 days now and the subject of this feed).

Is it possible that the same issue regarding non display of server settings is also the same problem that has been crashing Thunderbird?

Are you, or someone in technical support able to somehow reset my lineone.net account for me as I can't lose any of the emails currently stored there?

When Thunderbird crashes it locks out my system so I have to do a hard reboot. As Windows is not shutting down when this  happens I have ended up with a corrupt C: drive and have had to load a full image backup to get my system to boot again.

This took over 4 hours and is the second time I have had to do this.

Please help as this is causing me many problems and I have spent 5 days now trying to resolve this.

Regards Tony

I

[amahle-TT]

Hi there, if you still cannot see the server settings in your email client, consider removing the account and re-adding it using the automatic setup option. This often resolves configuration issues.

Also please ensure that your email client is updated to the latest version, as older versions may not support newer security protocols.

[argchichester]

@kanya-TT 

ok, I will look into it.

Can you help me with another issue please?

I am trying to  check the settings for my lineone.net account.

However, when I go into settings/accounts/manage your accounts and click on the Edit button for lineone.net there are no details of the server settings etc - only the option to select the standard folders. Also, the "X" Delete button is greyed out

My tiscali.co.uk account lets me view and modify the server settings and password etc.

It feels as if my lineone.net account is somehow locked or protected in some way. Is that possible?

How do I get to my lineone.net settings please?

[argchichester]

@nameunknown_ 

Sorry, I really didn't mean to offend you I am just so frustrated with this as I have lost the past 3 days worth of sent emails and spent hours trying to resolve this issue.  I must have rebooted my system 20 times or more now 😫.

Yes, I have checked crash logs but there aren't any present and the sent files are also missing  in web mail.

Thank you for your suggestions to help, it is much appreciated.

Please accept my humble apologies I know you are trying to help me. I am just old, tired and ratty today.

Best regards Tony