Depending on the software you are using, you may need to change the outbound (from) address of outbound email. In this How-To, we will change the outbound email address from “apache@example.com” to “webmaster@example.com”.
To start out, go to your postfix directory and modify/create your generic file. Your generic file will map the two addresses to each other. At the end of your generic file add a space or tab seperated file simmiler to this.
apache@example.com webmaster@example.com
Once you have added the entries to your generic file, you need to hash the file so postfix may quickly access it.
postmap /etc/postfix/generic
After you map has been created, you will need to add the entry to your main.cf file to tell Postfix to use your generic map.
smtp_generic_maps = hash:/etc/postfix/generic
Once you have updated your main.cf file, you need to reload postfix
postfix reload
This approach makes some fairly unconsidered assumptions.
Such as what?