Configure a Linux mail server¶

Set dns records¶

Choose a mail domain <your mail domain> that forms the end of the email address: <user name>@<your mail domain> e.g. me@example.com. Select a subdomain <your mail subdomain> of <your mail domain> that form together the host name <your mail subdomain>.<your mail domain> of the server like mail.example.com.

Set a AAAA and A records for <your mail domain> and <your mail subdomain> pointing to the server.

Set a MX record for <your mail domain> with {priority: 10, value: <your mail subdomain>.<your mail domain>, TTL: 86400}

Install postfix¶

apt install postfix Select postfix configuration “Internet site” Select <your mail domain> as the system mail name

Set mailbox size limit¶

Set a maximum mailbox size by editing the line starting with mailbox_size_limit = in the file /etc/postfix/main.cf and change it into:

mailbox_size_limit = 30000000

Restart the mail server and restart the system

postfix reload
reboot now

Testing sending and receiving mails¶

Send mail

echo "Some text" | sendmail my@mailaddress.com

Received mails end up in the file /var/mail/<username>

Rejecting all incoming mail¶

Edit /etc/postfix/main.cf and set inet_interfaces to loopback-only as described here.

In order for this change to take effect run postfix reload and restart the server.

Automatic upgrades¶

See this guide

Strange MX record behavior¶

MX Records on Hetzner are strange If the target domain name is the same as the current one one has to write only the subdomain without the domain. So “mail” instead of “mail.example.com”. If the target is different the domain name has to end with a dot. If the target domain name is the same as the current one and the full domain name ending with a dot is specified in the record sending mails per GMX does not work for some reason.