How to purge messages in Thunderbird.

[VJ]

Hi
    It is a small question related to ThunderBird. I have set a property 
in my IMAP email account settings due to which the messages will not be 
moved to Trash when deleted, but will be marked as deleted. Now I want 
to have something which is similar to Purge in Outlook Express to delete 
the messages that have been marked as deleted.

I tried searching for it before writing this mail to the list.

Regards from
VJ