cannot telnet port 25 from other hosts

[ssoss S]

hi..  I found that I cannot telnet my linux box (fedora core1) via port 25 
(SMTP) but the SMTP service is started.  I can telnet to localhost via port 
25.  May I know where is the config to control and allow me to telnet 
mylinux 25 from other hosts??

FYI, my sendmail version is
[root at watcher root]# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 watcher.teasin.com ESMTP Sendmail 8.12.10/8.12.10; Wed, 28 Jul 2004 
22:19:17
+0800

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