Rated 5 out of 5 stars
All e-mailprograms should have a passwordprotection (personal keycode) built within. Thunderbird is simply the best. Love it - and besides - works perfect together with Gmail and IMAP activated.
Now we only wait for Thunderbird addressbook to get a sync-function, so it automatically syncs the addressbook with (for example) Gmails online addressbook. In waiting for that, the add-on "Zindus" is a good complement (even though it only sync e-mail- and phoneposts of the addressbook) I still give Zindus 4 of 5. Very good.