From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Thu, 30 Jan 1997 10:13:59 +0100
From: Boyd Roberts boyd@france3.fr
Subject: pop3
Topicbox-Message-UUID: 54cd6fb6-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19970130091359.f9J0JwNPZmhxpdRN5DvO3BNP3ZozNtfK45saG447Ygk@z>

the client should be a popfs.  the server could reply like ftp with:

    USER boyd
    +OK Encrypt challenge 123 for boyd.