Configure send-only mailserver for Systemmails

This guide shows how to install a send-only mailserver using postfix on Debian to automatically send emails e.g. of unattended-upgrades or cron-jobs.

1. Install postfix and mailutils:

apt install postfix mailutils

2. Configure postfix as Internet site:

Then enter the systemmail-name e.g.

3. Verify correct host-file entry:

It is important that the first DNS name of the local server ( contains the domain, otherwise some mail servers will reject the mails sent from this server because they can't verify the domain. So in our case the /etc/hosts file should look like this:

If test would stand before the system mails could be rejected.

4. Test the configuration:

sudo echo "Postfix Send-Only Server" | sudo mail -s "Postfix Testing" <address-where-the-mail-should-be-send-to>

The receiver addresses of the system mails are configured in /etc/aliases, the content can look like this:

# See man 5 aliases for format
root:           <target-mail-address>
postmaster:     root
nobody:         root
hostmaster:     root
webmaster:      root
www:            root

After changing /etc/aliases, run the following command to update the aliases database:


If the receiver address is properly configured through the /etc/aliases file, just add MAILTO=root to the top of each crontab file that should send emails.

  • linux/debian/configure-send-only-mailserver.txt
  • Last modified: 2023/07/30 12:09
  • by Zyzonix