POP accounts are used for e-mail. POP users download their entire mailbox from a POP server, manage their mail on their POP client, and then upload the mailbox back to the POP server.
If you've defined a virtual e-mail domain (Config--Networking--Mail delivery system (sendmail)--virtual e-mail domain), you can define virtual POP accounts. A virtual e-mail domain allows you to serve different e-mail domains from the same server.
Most of the parameters for a POP account should be filled in the same as a regular login account. See login if you need more information on login name, full name, home directory, user ID, and the mail settings.
You can't set the group for a POP user; all POP accounts are in the
popusers group.