ffimnsr / jmail

Send-only SMTP mail server in container 📧 + 🍺

jmail

jmail is a simple and lightweight mail server in a container. It's an SMTP-only mail server, so no incoming mails only outgoing. You can connect your servers and APIs to send emails for development and production.

Features

• Send SMTP mails for development and production use.
• Outgoing emails signed with DKIM.
• Lightweight, customizable and built with security in mind.

Installation & Usage

On a clean workstation do pull then run the container.

podman pull ghcr.io/ffimnsr/jmail:latest
mkdir -p ./{postfix-data,postfix-config,opendkim-keys}
podman run -d --name jmail -p 5587:587 \
  -h example.com \
  -e JMAIL_HOSTNAME=example.com \
  -e JMAIL_ORIGIN=example.com \
  -e [email protected] \
  -v ./postfix-config:/etc/postfix:z \
  -v ./opendkim-keys:/etc/opendkim/keys:z \
  -v ./postfix-data:/var/spool/postfix:z \
  ghcr.io/ffimnsr/jmail:latest

And lastly, check the logs if everything is working fine. The last thing to do before going to production is to setup correctly your A, SPF, DKIM, and DMARC records on your preferred public DNS.

Here is a sample podman quadlet that you can use on your machine if you're utilizing podman architecture:

[Unit]
Description=Jmail Service
Wants=network-online.target
After=network-online.target

[Container]
ContainerName=jmail
Image=ghcr.io/ffimnsr/jmail:latest
Pull=always
HostName=<mail-server-hostname>
Volume=/etc/container-configs/jmail/postfix-ssl:/etc/postfix/ssl:z
Volume=/etc/container-configs/jmail/opendkim-keys:/etc/opendkim/keys:z
Volume=/var/container-data/postfix:/var/spool/postfix:z
Environment=JMAIL_HOSTNAME=<mail-server-hostname>
Environment=JMAIL_ORIGIN=<mail-server-hostname or mail-origin>
Environment=JMAIL_ROOT_EMAIL=<root-email>
HealthCmd=["sh", "-c", "nc -vz localhost 25"]
HealthInterval=30s
HealthRetries=5
HealthStartPeriod=20s
HealthTimeout=3s
PublishPort=10587:587

[Service]
Restart=always

[Install]
WantedBy=multi-user.target default.target

Mail Checklist

This are the things you need to do before going to production:

• Setup A record pointing to your server IP.
  • Setup PTR records on your reverse zones if you are not using your rDNS hostname as mail server hostname.
• Setup MX records pointing to the A record.
• Setup DKIM to the one printed in the jmail logs.
• Setup SPF to your domain record and or to your ip address. The setup below is full reject/fail (bounce) and not soft fail (accept and record).

  v=spf1 a:<mail-server-hostname> ip4:<server-ip> -all
  

• Setup DMARC to strict. This specifies the policy to reject on main domain then reject also on subdomain.

  v=DMARC1;  p=reject; sp=reject; rua=mailto:catchall@<mail-server-hostname>
  

• Check if your IP is in email blacklists. De-list it.
• Test your emails on https://mail-tester.com.

License

jmail is licensed under the Apache-2.0 License. See LICENSE file for more details.