133 lines
7.0 KiB
Markdown
133 lines
7.0 KiB
Markdown
# docker-postfixrelay
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[](https://github.com/loganmarchione/docker-postfixrelay/actions/workflows/main.yml)
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[](https://hub.docker.com/r/loganmarchione/docker-postfixrelay)
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Runs Postfix (as a relay) in Docker
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- Source code: [GitHub](https://github.com/loganmarchione/docker-postfixrelay)
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- Docker container: [Docker Hub](https://hub.docker.com/r/loganmarchione/docker-postfixrelay)
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- Image base: [Alpine Linux](https://hub.docker.com/_/alpine/)
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- Init system: [dumb-init](https://github.com/Yelp/dumb-init)
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- Application: [Postfix](http://www.postfix.org/)
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- Architecture: `linux/amd64,linux/arm64,linux/arm/v7`
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## Explanation
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- This runs Postfix (as a relay) in Docker.
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- Most home ISPs block port 25, so outbound emails must be relayed through an external SMTP server (e.g., Gmail).
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- This container acts as a single collections point for devices needing to send email.
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- ⚠️ Postfix acts as an open relay. As such, this is not meant to be run on the internet, only on a trusted internal network! ⚠️
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```
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Internal (LAN) network Public internet
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------------------
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| Device sending | | |
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| email alert | ------------- | |
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| | | | |
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------------------ | | |
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| | F |
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------------------ v | i |
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| | ------------------ | r | ----------------------------- -------------------
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| Device sending | | | | e | | | | |
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| email alert | ----> | This container | --| w |--> | SMTP server (e.g., Gmail) | ----> | Recipient email |
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| | | | | a | | | | |
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------------------ ------------------ | l | ----------------------------- -------------------
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^ | l |
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------------------ | | |
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| | | | |
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| Device sending | | | |
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| email alert | ------------- | |
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------------------
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```
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## Requirements
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- You must already have an account on an external SMTP server (e.g., Gmail, AWS SES, etc...).
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- Your external SMTP server must be using encryption (i.e., plaintext is not allowed)
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## Docker image information
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### Docker image tags
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- `latest`: Latest version
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- `X.X.X`: [Semantic version](https://semver.org/) (use if you want to stick on a specific version)
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### Environment variables
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| Variable | Required? | Definition | Example | Comments |
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|-------------|---------------------------|---------------------------------------------|----------------------------|--------------------------------------------------------------|
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| TZ | Yes | Timezone | America/New_York | https://en.wikipedia.org/wiki/List_of_tz_database_time_zones |
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| RELAY_HOST | Yes | Public SMTP server to use | smtp.gmail.com | |
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| RELAY_PORT | Yes | Public SMTP port to use | 587 | |
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| RELAY_USER | No | Address to login to $RELAY_HOST | SMTP username | |
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| RELAY_PASS | No | Password to login to $RELAY_HOST | SMTP password | If using Gmail 2FA, you will need to setup an app password |
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| TEST_EMAIL | No | Address to receive test email | receive_address@domain.com | If not set, test email will **not** be sent |
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| MYORIGIN | No | Domain of the "from" address | domain.com | Needed for things like AWS SES where the domain must be set |
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| FROMADDRESS | No | Changes the "from" address | my_email@domain.com | Needed for some SMTP services where the FROM address needs to be set, [fixes issue 19](https://github.com/loganmarchione/docker-postfixrelay/issues/19) |
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| MYNETWORKS | No (default: 0.0.0.0/0) | Networks that Postfix will forward mail for | 1.2.3.4/24, 5.6.7.8/24 | Single or multiple trusted networks separated with a comma |
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| MSG_SIZE | No (default: 10240000) | Postfix `message_size_limit` in bytes | 30720000 | |
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| LOG_DISABLE | No (default: false) | Setting to `true` disables logging | true | |
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### Ports
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| Port on host | Port in container | Comments |
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|---------------------------|-------------------|---------------------|
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| Choose at your discretion | 25 | Postfix SMTP server |
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### Volumes
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| Volume on host | Volume in container | Comments |
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|---------------------------|---------------------|------------------------------------|
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| Choose at your discretion | /var/spool/postfix | Used to store Postfix's mail spool |
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### Example usage
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Below is an example docker-compose.yml file.
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```
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version: '3'
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services:
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postfixrelay:
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container_name: docker-postfixrelay
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restart: unless-stopped
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environment:
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- TZ=America/New_York
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- RELAY_HOST=smtp.gmail.com
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- RELAY_PORT=587
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- RELAY_USER=your_email_here@gmail.com
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- RELAY_PASS=your_password_here
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- TEST_EMAIL=test_email@domain.com
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- MYORIGIN=domain.com
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- FROMADDRESS=my_email@domain.com
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- MYNETWORKS=1.2.3.4/24
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- MSG_SIZE=30720000
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- LOG_DISABLE=true
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networks:
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- postfixrelay
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ports:
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- '25:25'
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volumes:
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- 'postfixrelay_data:/var/spool/postfix'
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image: loganmarchione/docker-postfixrelay:latest
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networks:
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postfixrelay:
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volumes:
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postfixrelay_data:
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driver: local
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```
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Below is an example of running locally (used to edit/test/debug).
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```
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# Build the Dockerfile
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docker compose -f docker-compose-dev.yml up -d
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# View logs
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docker compose -f docker-compose-dev.yml logs -f
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# Destroy when done
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docker compose -f docker-compose-dev.yml down
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```
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## TODO
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- [x] ~~Add a [healthcheck](https://docs.docker.com/engine/reference/builder/#healthcheck)~~
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- [ ] Add TLS support for SMTPD and listen on 587
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