Sendmail Daemon Port Option

Having the following option in sendmail.cf will restrict receiving of mail only within the same host:

DaemonPortOptions=Port=smtp,Addr=127.0.0.1, Name=MTA

Further information of this option is found in the following page.

Note on default options are as follow:

• Address= specifies the address to listen on (default: all)
• Port= specifies the port to listen on (default: smtp (25))
• Family= specifies the protocol family (e.g., inet (IPv4) or inet6 (IPv6)) (default: both)

The proper way to configure the sendmail is not to edit the sendmail.cf directly but to change it in the sendmail.mc and then generate the cf file by issuing the command:

m4 sendmail.mc > /etc/sendmail.cf

The sendmail daemon will need to be restarted for the changes to take effect. Information on this can be found in the following

• RevSys
• Sendmail document 
• FAQs