Any possibility that your email provider is doing this for you?

Thanks Zenos, No, they are disappearing from my PC after I have read them.

Try right-clicking the Account 'Inbox' select 'Properties - Retention Policy Tab' Is there a check mark against 'Use My Account Settings'? If not checked, the radio buttons below will override the global setting in 'Account Settings - Disc Space' for just the selected folder (Inbox)

TB-38.3 Win10-PC

Hi Gild,

The 'Use My Account Settings' box WAS ticked, which may have somehow affected the 'Don't Delete Any Messages' as that was not selected in that 'Retention Policy Tab'. I'm a bit of a non-techie so I've unticked the box and made sure the 'Don't Delete Any Messages' is selected. Do you think that will do the job? ( I cannot find where or how to do what you suggested )

If the Retention Policy had a check mark against 'Use My Account Settings' then the other choices on that page should be grayed out, and the settings in 'Tools - Account Settings - (select account) Disk Space' should be in effect.

It may help to know what messages are disappearing? Are they from POP mail accounts, or from IMAP accounts? Are they all from a single folder in one mail account? From multiple folders, all in the same mail account? From multiple folders in several different mail accounts? From one or more folders in 'Local Folders'?

TB-38.3 Win10-PC

Thanks Gild,

All of my inbox, sent and deleted emails are separate sub-folders of 'Local Folders' in the one account on my Thunderbird email dashboard. The incoming and outgoing are POP mail accounts. When I look through the emails in those 3 areas, the 'Deleted' ones still left in there are from May 11 onwards, the 'Sent' that are still left are from June 10th onwards and the emails in the 'Inbox' still left are from July 24th onwards. All 'Starred' messages are all saved in those 3 folders though going right back. One thing I have noticed over the last few months is my PC is asking to compact folders more often than I thought would be necessary owing to the small number still left in there!!

If you have not compacted recently, your files may be bloated with old messages that have not been removed from the file.

Do not compact your folders until after you read the following article. Your missing messages might be recoverable.

http://kb.mozillazine.org/Undelete_a_message

All messages in a folder are stored in one large file. When you delete a message, it is only MARKED as deleted. It is not yet removed. The entire message is still in the file.

When you compact a folder, you force a re-write of the folder and remove all traces of the deleted messages, making the folder smaller in size. Messages marked as deleted are now unrecoverable, unless you have a profile backed up from just before the compacting was done.

The mozillazine article mentions a Thunderbird add-on 'Recover deleted messages' which links to - http://nic-nac-project.de/~kaosmos/index-en.html#recDelMsg which takes you to https://freeshell.de//~kaosmos/index-en.html#recDelMsg This is not an official Thunderbird site, but many users have downloaded Kaosmos add-ons without problems.

It may help.

TB-38.3 Win10-PC

Thanks Gild,

Although a lot of the missing emails are business related I can get by without them so I won't go down the path of trying to recover them as I'll possibly create more problems than they are worth! I'll just monitor the situation, be very vigilant in case any more disappear and if they do I'll work on the problem again.

Cheers!