There are various contexts in which users may need to authenticate themselves (i.e., supply a password): connecting to read their e-mail via a POP or IMAP client, setting up a personal mailbox filter, sending e-mail using SASL. PMDF supports performing such authentication against various authentication sources, such as system passwords, the PMDF password database, PMDF user profiles (PMDF MessageStore or PMDF popstore account profiles), or even an LDAP directory. The PMDF default, allowing authentication against any of a PMDF user profile, the PMDF password database, or system login passwords, is usually a good starting point for most sites. See the PMDF System Manager's Guide for further information on PMDF authentication and security configuration.