Hi there!

I configure a postfix for a small LAN without DNS, here's the tail -f /var/log/mail

l 14 11:25:15 linux postfix/smtpd[5423]: connect from localhost[192.168.2.51]
Jul 14 11:28:52 linux postfix/smtpd[5423]: lost connection after CONNECT from localhost[192.168.2.51]
Jul 14 11:28:52 linux postfix/smtpd[5423]: disconnect from localhost[192.168.2.51]
Jul 14 11:44:41 linux postfix/smtpd[5476]: connect from localhost[127.0.0.1]
Jul 14 11:44:41 linux postfix/smtpd[5476]: fatal: net/mask pattern 192.168.2.51/24 has a non-null host portion; specify 192.168.2.0/24 if this is really what you want

thanks;
Bronx73

Where is you setup pulling 192.168.2.51/24 from?