Try to rebuild the index file of the troubled folder. Right-click the folder - Properties - Repair Folder

thanks for your remark Christ1, however, it doesn't work

I have 3 POP accounts and 4 IMAP accounts.

The Delete function works oke on the IMAP accounts.

so it looks more like a POP / IMAP issue ..

Does using the file button to move messages to Trash work? That button is in the customize window.

All remove or delete functions work perfectly on IMAP accounts..

but Not on POP accounts..

grrrr

have you right clicked the trash folder and selected empty? It just might be they are full.

After emptying trash, you should compact the folders. The old messages will not actually go until you do that. http://kb.mozillazine.org/Keep_it_working_-_Thunderbird

I think i have found the problem, From all the POP accounts the "trash" map is gone..it looks like this is happened after running REGCURE PRO.

can anyone help me to restore these folders.

I would love it is you could reproduce that after the folder is recreated. There have been reports of the folder going missing for around a year. But no one has actually found a cause or a real link to the cause.

Simple create a new folder called whatever it was. You say trash.

install this addon https://addons.mozilla.org/en-US/thunderbird/addon/folderflags/?src=ss and give the folder the correct trash flag. This will reset it's "special" status and icon.

Instructions to install http://chrisramsden.vfast.co.uk/3_How_to_install_Add-ons_in_Thunderbird.html

Hi Matt,

your solution did solve the problem.

and as you asked i tried to recreate the problem.

When using the program RegCure PRO it delets the trash folder.

i have made an printscreen of this.

maybe a good idea to inform them oficcially that their cleaning software corrupts the POP email accounts

You should examine "registry cleaners" very carefully before using them. Many of them will remove things from the registry that are not junk.

TevredenLefty said

I think i have found the problem, From all the POP accounts the "trash" map is gone..it looks like this is happened after running REGCURE PRO. can anyone help me to restore these folders.

I have had similar problems after running a Registry cleaner (including the one you mention using). Twice. I will never use one of those again.