re :I have a strange black square that appears when replying to emails. It can be moved with the cursor but won't disappear.

Post an image showing the issue because it does sound unusual.

re :In the Deleted folder, when I empty it, either using 'Empty Deleted' or manually be selecting all the messages and using the delete key, The number of messages drops to zero but the disc space is still occupied. This is in contrast to the junk folder where the operation works as expected.

On pop account and 'Local Folders' account..I get the exact opposite :) Empty Junk removes the emails, but folder has not been compacted so therefore the Size of folder will remain until Junk/Spam gets compacted. Empty Deleted removes emails and does not show size.

However, I also run a beta version of Thunderbird and Pop accounts in release version are set up as Imap accounts in this beta version. In Imap accounts : Empty Junk removes the emails, so count is not displayed but size remains, but only until I select another folder, then size is removed - so obviously a synchronsing delay. Empty Deleted removes emails, so count is not displayed but size remains, but only until I select another folder, then size is removed - so obviously a synchronsing delay.

So, in Imap accounts, I discover, the size is reduced but not until I select another folder.

But 'Local Folders' which also has a deferred pop account using it - That is the same as the release version : Empty Junk removes the emails, but folder has not been compacted so therefore the Size of folder will remain until Junk/Spam gets compacted. Empty Deleted removes emails and does not show size.

So, it seems you should get a different result depending upon whether imap or pop or Local Folders. You may also find certain servers can auto delete emails off the server if they are in the trash. Gmail do it every 30 days, but some do it every 7 days and I've even come across some that do it in less time. It means, you may have emails in Trash, you select Trash to check on them only to discover this is an imap account and the Trash has now synchronised with server and suddenly a load of emails disappear before your eyes. Imap folders can only display whatever is displayed on server.

Examples: Yahoo server does this:

• Trash deletion frequency - Trash is deleted after 7 days.
• Spam deletion frequency - Spam is deleted after 30 days.

Xfinity server does this:

• Flagged spam: deleted after seven days
• Trash: deleted after 14 days

The black square appears as soon as I start typing but, if I move the cursor, it disappears until typing recommences. I've had to send you a photo because screen shots change the conditions. I hope this is of use.

Thanks for your help.

Regards, Paul