Sorry - I also meant to add that I have found a couple of posts detailing the same problem and I have tried the proposed solutions of compacting and repairing the accounts. These do not seem to work either

I've been using Thunderbird for 8 months and I haven't found a solution to this. I have several times thought I had found some thing/behavior/option that made it go away but it comes back. For awhile I thought that having the Thunderbird activity manager window up made the problem go away because I ran for several weeks like that without an incident. You'll see that posted in quite of few of the other threads as well. (Not specifically the activity manager - everyone has a period without the problem and they think it must be the last change they made - but it's never the same change.) For me the time between hangs has varied from approximately 4 hours to about 4 weeks so it's a pain to try to pin it on anything.

I've also compared add-ons and settings can can't find anything obviously in common with the others that have it. Happens in 24 - 3x versions at least. Compact/repairing seems to be a generic "try this" sort of solution for any odd behavior but doesn't seem to relate to this issue.

Also, I believe I have seen it reported on Windows, OS X and Linux with a wide selection of AVs an no AV in one case. So there seems to be a piece of core code that just mysteriously gets unhappy in conditions that no one has been able to pin down yet. If you ever find anything that works for you - please let us know!!!

Its kinda good to know DaveH - that I am not the only one and it is nothing stupid or obvious that I have done.

I too have disabled and then removed all addons and extensions in case one of them was causing a conflict somewhere.

Recently even the shutting it down and then reopening hasn't always worked either. Everytime I think I have nailed the cause (ie the condition) it then goes and does something to prove me wrong. Very, very frustrating as I really don't want to go back to Outlook but having proof of emails sent is sometimes extremely important in business.

So if there is anyone out there that can shed some more light on this it would be extremely wonderful

Why don't you like Outlook?

I'm the defacto IT guy for my family and I've had a bunch of PCs sitting here waiting for a stable version of Thunderbird so I can ship them out. After half a year of waiting, I have no idea if we're any closer to that ever happening.

As such, I think if I want to get these out this year, I may have to choose another email client. So, I'm curious about your thoughts about one of the contenders.

I still like TB when it works, but most of the people who will be receiving these computers have been running Eudora since the 90s and they've never had a glitch. If Eudora did UTF-8 and had good integration with GPG, we'd probably all stay with that "forever." "Good enough" and "always works" trumps "nice when it works" especially when you're the guy who's going to get the calls and emails.

The main reason for changing from Outlook to TB was because the file that stored your emails was just one huge file. I have had a customers corrupted which came with a bad sector on the hard drive and it took us ages to get the hard drive just to copy that monstrosity of a file. We thought we were going to lose all her saved emails. My business partner has been using TB for years without a glitch although on a linux machine. (So had his wife on a windows machine.) He recommended TB as it saves all the emails as separate files and said it was far superior for the purposes of recovery and backups.

Then a few months later my outlook file became corrupted so I thought I would try TB so that I would never be at risk of losing the whole lot again.

But it is obviously a far more stable programme, despite the lack of judgement designing it to save everything in one huge lump.

The way in which you create your signature, how you organise your multiple accounts is also easier to use... but TB is free and doesn't try to tie you into other MS stuff.

I have not tried any other email client, but would be open to suggestions.

This could have many causes, but starting at the beginning is the question of if the folder is local or synchronized to a mail server through IMAP.

The next question is what mail provider? both Google and Microsoft in defiance of the RFCs for mail add mail sent through their SMTP servers to the sent folder of the account. This can lead to contention issues or duplication. Depending on the day really. For Those type accounts changing the account settings to NOT sdave sent mail or location it to local folders as a backup is the best option.

Compaction of the sent folder and maintaining it's size below 4Gb is almost essential. While Thunderbird maintains that IMAP folders greater than 4Gb are Ok, I am yet to be convinced.

Then there are the bug https://www.google.com/search?q=saving+sent+site%3Abugzilla.mozilla.org&ie=utf-8&oe=utf-8