If you can rule out having deleted your inbox inadvertently in TB, which would probably have synchronised the deletion with your server: could it be a problem on your IMAP server (-provider)? Things do happen occasionally.

You may have come across how to undelete a message, if applicable in your case, or deleting messages in IMAP accounts for some useful settings (see mail and news settings for almost all settings in Config Editor).

I've never had such a problem, using several IMAP accounts for years.

One additional thing I do though, is forwarding all incoming mails of the most important mail account to another IMAP account just for backup purposes. I won't have this backup account in TB, so I'd have to purge mails on this backup account manually (e. g. webmail) every now and then. Another exotic option would be to have two accounts set up in TB for one and the same real mail account, but one is set up in TB as IMAP and one as POP with "Leave messages on server" checked. Since the POP backup will store all mails on your local file system it won't help in case of a local disk failure if you don't backup your profile.

Having clever IMAP Synchronization settings that fit your needs, certainly keep messages for this account on this computer, may protect you in some cases.

Other than that I'm afraid there isn't much help other than the usual stuff that you'd also do when protecting an important local filesystem folder (basically, frequent backups I guess).

http://kb.mozillazine.org/Disappearing_mail

Do you have a backup of your profile folder?

Hi, Thanks for the answers so far.

Christ1 - No I don't have a backup of my profile folder. My profile folder is currently 10 GB, I'm not really sure where or how I would copy it as clearly the way TB works making a copy whilst the profile is in use would not work.

I am using TB from 3 computers so I guess I'd have to shutdown TB on all 3 machines and make a backup on one of them.

I've been using Thunderbird for a while, I actually have it running on 3 computers (all Linux) and I have 11 email accounts currently active.

The emails are coming from 2 Hostgator servers and there is nothing to indicate a problem there.

It was only the inbox for one account that got cleared (on the server so it cleared the content of the inbox on all 3 of my machines).

I'd really like to know what caused this as it has never happened before and I can see nothing in my setup to suggest a problem.

Appreciate the help.

It was only the inbox for one account that got cleared (on the server ...

Have you checked with your email provider? If the messages disappeared on the server first, it's obvious that they would get deleted in Thunderbird as well. In that case I don't see how Thunderbird is at fault.

My profile folder is currently 10 GB

That's rather large, but shouldn't cause problems for Thunderbird in the first place. I'd rather expect you'll hit the storage limit on your provider's server at some point.

I'm not really sure where or how I would copy it

Where - that's entirely up to you. How - it's as simple as copying the profile folder to somewhere else. http://kb.mozillazine.org/Thunderbird_:_FAQs_:_Backing_Up_and_Restoring#Manually_back_up_the_profile As you just found out, using IMAP isn't a replacement for a backup.

as clearly the way TB works making a copy whilst the profile is in use would not work.

Close Thunderbird before backing up the profile.

Christ1 - my single gmail account has 8 GB of mail in, so I didn't think 10 GB for 11 IMAP accounts in TB was even remotely large. I shouldn't run into space issues on the servers for years yet. I actually have over 40 email accounts I need to configure, just haven't finished setting up TB yet.

I have no idea how or why these messages all disappeared, so I don't know if it was TB that did it or for some reason the server. I don't see why it would be the server. There were only perhaps 50-100 emails (its a new account for a new project) but they were all very important.

Using POP and leaving messages on the server - won't that get messy when I'm pulling the mail down onto 3 separate computers? I use IMAP because it keeps everything synchronised (unfortunately also mass deletions!).

I'm actually considering just using webmail, but don't much like the idea of having to have 40+ browser tabs open and flick through them looking to see if any accounts have new mail. But I can't find any mail checker that works with Linux Mint to alert me to new mail on my servers.

Once again thanks for the advice.

Using POP and leaving messages on the server - won't that get messy when I'm pulling the mail down onto 3 separate computers?

Yes, using POP probably wouldn't be a good idea for you.

I'd still suggest to check with your email provider if something went wrong at their end. Beyond that, take a look at this article. http://kb.mozillazine.org/Disappearing_mail