As an aside, my understanding was that vpopmail user should have /sbin/nologin as shell (or your flavor's equivalent...).
That's incorrect, it can cause problems with maildrop and other programs in .qmail (or .qmail-alias files) that use the SHELL environment variable.
If the account doesn't have an encrypted password ("!!" in the password field of /etc/shadow), then no one will be able to log into it.
-- Tom Collins - [EMAIL PROTECTED] QmailAdmin: http://qmailadmin.sf.net/ Vpopmail: http://vpopmail.sf.net/ Info on the Sniffter hand-held Network Tester: http://sniffter.com/