I know for 'strike when deleted' and delete attachment after # days' from Horde (http://www.horde.org/images/screenshots/webmail/imp_1_1.png), if you have horde maybe you can mix somehow with your client or use only Horde.Thats the way I would normally do it, and the way I do it on Claws mail which I use. BUT when setting up the mail filters I stumbled across a menu that allowed either delete or hide as the options with age. The problem is I can't find it to alter the age at which to hide again. Maybe a hidden function, no pun intended.
I can't recall this options in Tbird but maybe they are dip hidden in some previous versions. Now I have 3.1.1 and cant find it anywhere.
-- Bye, Goran Dobosevic Hrvatski: www.dobosevic.com English: www.dobosevic.com/en/ Registered Linux User #503414