Again; the out bound email is on port 25 and inbound on 110 or 143 --- BUT
the network admin CAN block those to your client systems and thus you get NO email
access.
to test if access to POP is possible, you need the pop server name for your mailbox --
frequently it is something like pop.domainname.com
get a command prompt and enter
telnet pop.domainname.com 110
(substitute your pop server name but keep 110)
if the admin has NOT blocked pop3 access, you should get back
+OK POP3 server ready.
If this fails, then it is blocked and you need to discuss this with the admin
just configure your email client {thunderbird , outlook express} for normal access