docker-made-special-mail

Based on https://github.com/lava/dockermail

A secure, minimal-configuration mail server in a docker container.

This repository is tailored to small private servers, where you own some domain(s) and want to receive the mail for and send mail from this domain.

The SMTP and IMAP server. This container uses postfix as MTA and dovecot as IMAP server. All incoming mail to your own domains is accepted. For outgoing mail, only authenticated (logged in with username and password) clients can send messages via STARTTLS on port 587. Outgoing mail is configured to get OpenDKIM signature, you need to generate a key and set up your domain records. Also you should add PTR record to your IP (aka reverse DNS) which is done by your server provider and add an SPF record to your domain - otherwise you may get your mail spam filtered.

Setup

Create 2 folders: one for mail configuration (/opt/dockermail/settings), another for mail storage (/opt/dockermail/vmail). Use the the example config files in dovecot/example of this repo.

1. Add all domains you want to receive mail for to the file /opt/dockermail/settings/domains, like this:

   example.org example.net

2. Add user aliases to the file /opt/dockermail/settings/aliases, like

   johndoe@example.org john.doe@example.org john.doe@example.org john.doe@example.org admin@forum.example.org forum-admin@example.org @example.net catch-all@example.net

An IMAP mail account is created for each entry on the right hand side. Every mail sent to one of the addresses in the left column will be delivered to the corresponding account in the right column.

3. Add user passwords to the file /opt/dockermail/settings/passwords like this

   john.doe@example.org:{PLAIN}password123 admin@example.org:{SHA256-CRYPT}$5$ojXGqoxOAygN91er$VQD/8dDyCYOaLl2yLJlRFXgl.NSrB3seZGXBRMdZAr6

To get the hash values, you can either install dovecot locally or use docker exec -it dockermail bash to attach to the running container and run doveadm pw -s <scheme-name> inside.

4. Change the hostname in file /opt/dockermail/settings/myhostname to the correct fully qualified domain of your server.

5. Add DKIM settings files: /opt/dockermail/settings/opendkim.conf and /opt/dockermail/settings/mail.private See https://help.ubuntu.com/community/Postfix/DKIM on the info about these settings. You will need to generate your own mail.private key and set up your domain records, the opendkim.conf from dovecot/examples is ready to use.

6. Build container

   make

7. Run container and map ports 25 and 143 from the host to the container. To store your mail outside the container, map /opt/dockermail/vmail/ to a directory on your host. (This is recommended, otherwise you have to remember to backup your mail when you want to restart the container)

   docker run -d -p 25:25 -p 587:587 -p 143:143 -v /opt/dockermail/settings:/mail_settings -v /opt/dockermail/vmail:/vmail dovecot_made_special/2.1.7

8. Enjoy.

Patches welcome!