This is a simple and minimal smtp server based on postfix. The goal is not to be a full-fledged email server but just to support web applications (for example Moodle) with sending notifications. It also provides simple forward email addresses (for example all emails sent to [email protected] are forwarded to [email protected]). It can support multiple email domains and multiple email addresses for each domain. To prevent spam and abuse from irresponsible people, it accepts to relay emails only from local networks (including local docker containers) and from specific ip addresses (where web applications are installed).
To send and receive emails, DNS has to be configured properly. For each email domain you need something like this on the DNS configuration:
smtp.example.org. IN A 10.11.12.13
example.org. IN MX 1 smtp.example.org.
example.org. IN TXT "v=spf1 mx -all"
Obviously, the port 25 has to be open in the firewall.
-
First install
dsandwsproxy: -
Then get the scripts from github:
ds pull postfix -
Create a directory for the container:
ds init postfix @smtp.example.org -
Fix the settings:
cd /var/ds/smtp.example.org/ ; vim settings.sh -
Build image, create the container and configure it:
ds make -
Get a letsencrypt SSL certificate with:
ds get-ssl-cert -
For more details see INSTALL.md
Configuration files are on the directory 'config/'. There you can add
more email domains, aliases, or allow hosts/networks to use the server
for relaying (sending) emails. You need to run ds inject update.sh
after making changes to the config files.
If you add a new email domain, you should also create a new DKIM key
for it and add the corresponding configuration as a TXT record on the
DNS server: ds dkimkey add <email-domain>
ds stop
ds start
ds shell
ds help