pmb-pf/README.md
2021-02-03 18:40:28 -05:00

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# docker-postfix
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Simple Postfix SMTP TLS relay [docker](http://www.docker.com) alpine based image with no local authentication enabled (to be run in a secure LAN).
It also includes rsyslog to enable logging to stdout.
_If you want to follow the development of this project check out [my blog](https://www.juanbaptiste.tech/category/postfx)._
### Available image tags
Currently we only handle a rolling release of new versions so only _latest_ tag is available, but there is [work in progress](https://github.com/juanluisbaptiste/docker-postfix/pull/29) to start releasing versioned images to be able to pin to specific versions in production deployments.
*_NOTES_*:
* The _alpine_ tag has been switched to use the master branch, but it's irrelevant as it is the same as _latest_.
* Old CentOS 7 based image is avaiable on the _centos_base_image branch_, but it is not being developed any more.
### Build instructions
Clone this repo and then:
cd docker-Postfix
sudo docker build -t juanluisbaptiste/postfix .
Or you can use the provided [docker-compose](https://github.com/juanluisbaptiste/docker-postfix/blob/master/docker-compose.override.yml) files:
sudo docker-compose build
For more information on using multiple compose files [see here](https://docs.docker.com/compose/production/). You can also find a prebuilt docker image from [Docker Hub](https://registry.hub.docker.com/u/juanluisbaptiste/postfix/), which can be pulled with this command:
sudo docker pull juanluisbaptiste/postfix:latest
### How to run it
The following env variables need to be passed to the container:
* `SMTP_SERVER` Server address of the SMTP server to use.
* `SMTP_PORT` (Optional, Default value: 587) Port address of the SMTP server to use.
* `SMTP_USERNAME` Username to authenticate with.
* `SMTP_PASSWORD` Password of the SMTP user. If `SMTP_PASSWORD_FILE` is set, not needed.
* `SERVER_HOSTNAME` Server hostname for the Postfix container. Emails will appear to come from the hostname's domain.
The following env variable(s) are optional.
* `SMTP_HEADER_TAG` This will add a header for tracking messages upstream. Helpful for spam filters. Will appear as "RelayTag: ${SMTP_HEADER_TAG}" in the email headers.
* `SMTP_NETWORKS` Setting this will allow you to add additional, comma seperated, subnets to use the relay. Used like
-e SMTP_NETWORKS='xxx.xxx.xxx.xxx/xx,xxx.xxx.xxx.xxx/xx'
* `SMTP_PASSWORD_FILE` Setting this to a mounted file containing the password, to avoid passwords in env variables. Used like
-e SMTP_PASSWORD_FILE=/secrets/smtp_password
-v $(pwd)/secrets/:/secrets/
* `ALWAYS_ADD_MISSING_HEADERS` This is related to the [always\_add\_missing\_headers](http://www.postfix.org/postconf.5.html#always_add_missing_headers) Postfix option (default: `no`). If set to `yes`, Postfix will always add missing headers among `From:`, `To:`, `Date:` or `Message-ID:`.
* `OVERWRITE_FROM` This will rewrite the from address overwriting it with the specified address for all email being relayed. Example settings:
OVERWRITE_FROM=email@company.com
OVERWRITE_FROM="Your Name" <email@company.com>
To use this container from anywhere, the 25 port or the one specified by `SMTP_PORT` needs to be exposed to the docker host server:
docker run -d --name postfix -p "25:25" \
-e SMTP_SERVER=smtp.bar.com \
-e SMTP_USERNAME=foo@bar.com \
-e SMTP_PASSWORD=XXXXXXXX \
-e SERVER_HOSTNAME=helpdesk.mycompany.com \
juanluisbaptiste/postfix
If you are going to use this container from other docker containers then it's better to just publish the port:
docker run -d --name postfix -P \
-e SMTP_SERVER=smtp.bar.com \
-e SMTP_USERNAME=foo@bar.com \
-e SMTP_PASSWORD=XXXXXXXX \
-e SERVER_HOSTNAME=helpdesk.mycompany.com \
juanluisbaptiste/postfix
Or if you can start the service using the provided [docker-compose](https://github.com/juanluisbaptiste/docker-postfix/blob/master/docker-compose.yml) file for production use:
sudo docker-compose up -d
To see the email logs in real time:
docker logs -f postfix
#### A note about using gmail as a relay
Gmail by default [does not allow email clients that don't use OAUTH 2](http://googleonlinesecurity.blogspot.co.uk/2014/04/new-security-measures-will-affect-older.html)
for authentication (like Thunderbird or Outlook). First you need to enable access to "Less secure apps" on your
[google settings](https://www.google.com/settings/security/lesssecureapps).
Also take into account that email `From:` header will contain the email address of the account being used to
authenticate against the Gmail SMTP server(SMTP_USERNAME), the one on the email will be ignored by Gmail unless you [add it as an alias](https://support.google.com/mail/answer/22370).
### Debugging
If you need troubleshooting the container you can set the environment variable _DEBUG=yes_ for a more verbose output.