Client accesses POP3--SMTP
1. The most commonly used email receiving protocol on the public network
two。 By default, the message is received locally in * .pst, and the server-side data is deleted.
Port for 3.POP3 counterpart: 110 dint POP3s port: 995
Port 25 used by 4.SMTP: 25 in ISA and TMG, port used in Exchange: 587
5.POP3 protocol only receives the "inbox" locally
6. The Exchange pop3 service is not started by default
