Install Postfix Install postfix and mailutils if not already installed: sudo apt install postfix mailutils Postfix Configuration Screen In the screens, that will show up when installing postfix: General type of mail configuration: Choose Internet Site System mail name: It will be the domain part of our emails, so if you choose the default which is the systems hostname e.g. serverhostname, Postfix will use the address someuser@serverhostname You can use serverhostname.