Too long to access webmail/pop3

How long to make webmail/pop3 work?
There are 2 email box in my domain: with pop3 username: michael with pop3 username: m1234567
The user michael also the ftp/shell account name and the works with webmail/pop3 within 2hours but the still can not work. It’s 2days ago.

How to do now? still wait or make some change?