postfix doesn't receive message

Hi everybody

I install postfix, just basic thing for local network ( to receive from other machine in my local area : 192.168.100.0/24)
from other machine for example 192.168.100.25 I receive mail if I use telnet
            telnet 192.168.100.100 25
but with mail   bela@192.168.100.100
I didn't receive anything here is the two connection from the remote machine 100.25 to the server 100.100

user@debian25:~$ telnet 192.168.100.100 25
Trying 192.168.100.100...
Connected to 192.168.100.100.
Escape character is '^]'.
220 server312.iap.dz ESMTP Postfix (by Bela Debian/GNU)
HELO server312.iap.dz
250 server312.iap.dz
MAIL FROM: user@debian.25
250 2.1.0 Ok
RCPT TO: bela@server312.iap.dz
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Hello There
with telenet 25
.
250 2.0.0 Ok: queued as 2FAEF3B20
QUIT
221 2.0.0 Bye
------------------------------------------------
Connection closed by foreign host.
user@debian25:~$ mail bela@192.168.100.100
Subject: With mail command
Hello there with mail command
.
cc:
-----------------------------------------------------------------

bela@server312:~$ mail
Mail version 8.1.2 01/15/2001. Type ? for help.
"/var/mail/bela": 1 message 1 new
>N 1 user@debian.25     Sat Feb 6 11:47   11/361
& 1
Message 1:
From user@debian.25 Sat Feb 6 11:47:19 2010
X-Original-To: bela@server312.iap.dz

Hello There
with telenet 25

The last part is what I receive with telnet 25
Here is my main.cnf

myhostname = server312.iap.dz
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = server312.iap.dz, localhost.iap.dz, localhost
relayhost =
mynetworks = 127.0.0.0/8 192.168.100.0/24
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
html_directory = /usr/share/doc/postfix/html

thanks for help