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!

[argchichester]

Thank you @Gliwmaeden2  I have entered the information as suggested.

[argchichester]

Many thatks for your message @Mandisa-TT 

There is no obvious pattern that I can see and the propblem arises with every email I send from my lineone.net account.

Another thing I have noticed is that messages are not being saved in the draft folder. There is a header record present but no email content. It would appear that when the system attempts to backup to draft the problem arises and the system locks out requiring a hard reboot.

This is only happening on my lineone.net account - the tiscali.co.uk account is working correctly.

In an attempt to fix this, I have rebuilt my C: drive from a full backup (made when everything was working) but the error is still present so it would appear to me that the problem is not to do with Thunderbird so must be to do with my TalkTalk account.

Web mail continues to work correctly.

Any more ideas would be much appreciated.

[Mandisa-TT]

Hi @argchichester I have checked on your account and I do see that both your email addresses are linked to your broadband account. Have you noticed any patterns in when the crashes occur (e.g., after sending a certain type of email)?

[Gliwmaeden2]

Have you listed ALL your legacy email addresses from older accounts, as suggested here, @argchichester, to be put in Private Notes and Save changes?

https://community.talktalk.co.uk/t5/Email/Important-information-about-changes-to-your-TalkTalk-Email...

Customers with current Broadband packages but using older addresses are having problems sending. 

Please make sure that everything is fully up to date in your Community profile for staff to make headway during the day.