ricardopereira / docker-mail

Build an email server image for Docker

docker-mail

A mail server in a box.

"A secure, minimal-configuration mail server in a docker container" based on lava/dockermail.

"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. It consists of 2 separate docker containers:

• dovecot: The SMTP and IMAP server with DKIM. 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. In theory it works with all mail clients, but it was only tested with Mail.app.

• mail-base: This image is just an implementation detail. It is a workaround to allow sharing of configuration files between multiple docker images."

Setup

You need to clone the repository or extract the source to a accessible docker machine.

1. Add all domains you want to receive mail for to the file mail-base/domains, like this:

   example.org example.net

2. Add user aliases to the file mail-base/aliases, like

   [e-mail] [e-mail] [e-mail] [e-mail] [e-mail] [e-mail] @example.net [e-mail]

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 mail-base/passwords like this

   [e-mail]:{PLAIN}password123 [e-mail]:{SHA256-CRYPT}$5$ojXGqoxOAygN91er$VQD/8dDyCYOaLl2yLJlRFXgl.NSrB3seZGXBRMdZAr6

To get the hash values, you can either install dovecot locally or use lxc-attach to attach to the running container and run doveadm pw -s SHA256-CRYPT inside.

4. Add ssl certificate files to dovecot/cert.

• cert.pem: ssl bundle
• key.pem: private key

5. Change MAILHOST env variable from dovecot/Dockerfile.

Change opendkim.keys file

Change opendkim.sign file

Change opendkim.trusted file

Change postfix.main.cf:

myhostname = example.com
mydestination = mail.example.com

Change dovecot.lda:

hostname = example.com

6. Build containers:

   make

7. Copy DKIM string from output for domain service, something like

   mail._domainkey.example.com v=DKIM1; k=rsa; p=<COPY_DKIM_STRING>

8. Run container:

   make start

9. Stop container:

Execute docker ps and get the id of the running container associated with the mail. Then docker stop <pid> to finish the container.

Mail log

You can check on /var/log:

• mail.log: debug information and status.
• mail.err: critical errors.

Known issues

• Changing any configuration requires rebuilding the image and restarting the container
• No spam filter