Please elaborate a bit so I fully understand the issue. eg: you cannot empty the 'Trash' folder? OR clicking on 'Delete' for an email in eg: 'Inbox' does nothing?

Deleting and creating a new Trash folder, should have cleared all emails in the Trash. Please confirm.

If you cannot delete an email in eg: 'Inbox' it is possible the 'Inbox' is suffering from some corruption.

Please do the following: 'Move' all good wanted emails from 'Inbox' to another suitable folder for storage. Try to delete everything that is left in Inbox. Regardless of whether you manage to delete them.... right click on 'Inbox' folder and select 'Compact'

Strongly recommend you frquently compact the 'Junk' folder as emptying Junk does not fully delete the emails.

Usually, you do not need to move all emails before compacting a folder, but it is a wise thing to do if you suspect something is not quite right with the folder. Good info on compacting - what it does and why it is important. http://kb.mozillazine.org/Compacting_folders

Did the compacting get the 'Inbox' working again?

Thanks for your interest. My problem is delete messages from Inbox (does not move messages into Trash folder). The proposed solution above does not work yet, but after several attempts I try this simple procedure and everything goes back to normal:

1) Create Trash subfolder 2) Empty Trash

I hope that can help someone else. Hello everybody.