Setup

…on debian to send all emails received with mail by itself to the target. Install mailutils and exim4 (Both required!) and add desired target (maybe forward root to your own user) by adding some lines like [USERNAME]: [EMAIL] to the following file:

sudo apt-get install mailutils exim4
sudo nano /etc/aliases

Local email

1. Run sudo dpkg-reconfigure exim4-config and select internet site (confirm everything with return…)
2. Add [USERNAME] to the mail group: sudo adduser [USERNAME] mail
3. Enjoy you local email service!

Email with remote SMTP server

If you want to use this feature and don’t need to authenticate against the SMTP server you should check the lighter postfix mailserver out.

1. Run sudo dpkg-reconfigure exim4-config and select mail sent by smarthost; no local mail
2. Enter at IP address or host name of the outgoing smarthost your smtp server like [SMTP_SERVER_HOST]::[PORT_587]
3. Add the credentials to the local config: sudo nano /etc/exim4/passwd.client: [SMTP_SERVER_HOST]:[USERNAME]:[PASSWORD]
4. Restart exim4 with sudo systemctl restart exim4
5. Test with: mail -s [SUBJECT] and CTRL-D

Override From-Server domain

…just by filling out the fields at the dpkg-reconfigure command correctly an then enabling the option Hide local mail name in outgoing mail? (the visible internal system name does matter, if you wish to still be able to distinct e.g. the root-user of two machines. Otherwise their domain name will be replaced to the server name and in this case also the aliases won’t work). This ensures the domain name is corrected for every possible email-sending user - other than the following option, which allows the rewrite only for specific users (so you must fix e.g. root, netdata and so on seperatly on evey machine)!

Override From-Field completly

Some SMTP email servers really don’t like freely choosen sender emails. To bypass this add a new line to the file like [USERNAME]: [NEW_FROM_EMAIL]:

sudo nano /etc/email-addresses

Something wrong?

…or you don’t get the sent emails? Send some emails manually with mail -s [SUBJECT] [TARGET_EMAIL_OR_LOCAL_USERNAME] and CTRL-D and watch the logs with sudo tail -f /var/log/exim4/mainlog or sudo tail -f /var/log/exim4/paniclog…