Configuring postfix to only send to a specified domain

Question

In order to not accidentally send real emails to people outside the company from an integration test server, I'd like to configure postfix to only send emails to addresses like *@somecompany.com and drop all other emails. Is it possible to somehow configure it in /etc/postfix/main.cf and if yes then how?

Answer 1

You can specify like that with the help of /etc/postfix/transport file You can add the line transport_maps = hash:/etc/postfix/transport in main.cf Do the steps below Create a transport - transport1 and Mail sent to user "user@gmail.com" should go through transport1 and all other mail sent should go through default.

First stop dual instances of postfix if any. Open /etc/postfix/main.cf and set inet to all.

• Add the following to master.cf

  transport1      unix    -       -       n       -       1       smtp
     -o smtp_bind_address= (add a space at 1st)
     -o syslog_name=postfix-localroute1 (add a space at 1st)
  

• Add/create the following to /etc/postfix/transport

  somecompany.com    transport1:

• Run postmap after defining the transport file.

  postmap /etc/postfix/transport

I have defined a transport above. It means all mail to @somecompany.com will go through you specifed in transport and that ip will not b displayed as it is in maillog. Instead it will be shown as postfix-localroute1

• Add the following to main.cf

  transport_maps = hash:/etc/postfix/transport

• Run:

  postmap /etc/postfix/transport

• Reload postfix:

  postfix reload