Pop_auth asks user for his APOP secret and stores this secret after encryption in ~/.spop3d file. Used
encryption is very weak and protects only from curious system administrator who accidentialy looks at
~/.spop3d file. Don't use your account password as the APOP secret!!!
Pop_auth will set APOP secret for all maildrop names specified in the command line. You can use the
special ! name to specify your default maildrop. If called without any arguments, pop_auth will set APOP
secret for the default maildrop.