rh+postfix only can send mail out ,why not recieve mail ?

handsome1234

rh+postfix only can send mail out ,why not recieve mail ?:help

handsome1234

my mail server hostname is mail.223.223.223.238 ,so i thinks dns is not needed ,
2,[root@mail root]# telnet 223.223.223.238 25
Trying 223.223.223.238...
Connected to 223.223.223.238.
Escape character is '^]'.
220 mail.223.223.223.238 ESMTP Postfix
so, what should i do ?because i can only send mail ,not recieve mail ,for eganple:
i use aa@223.223.223.238 send a mail to bb@223.223.223.238 by foxmail ,
send process is ok ,but when i use bb@223.223.223.238 to recieve ,find nothing
3:[root@mail root]# telnet 223.223.223.238 110
Trying 223.223.223.238...
Connected to 223.223.223.238.
Escape character is '^]'.
+OK POP3 [223.223.223.238] v2001.78rh server ready






!!!??why?????