sendmail-to-matrix

sendmail-to-matrix

Forward locally received emails (admin notifications, etc) to a Matrix room.

THIS PROJECT IS IN ALPHA, BUT IT WORKS AND I USE IT :)

Background

Proxmox can only send email notifications. Since they didn't work with the email service I wanted to use, I decided to use Matrix (which I use elsewhere anyway).

I wanted a minimal one-way bridge, wherein I could configure Proxmox to send email notifications to a local email address (matrix@localhost in my case) and the body of each email would be forwarded to my Matrix room.

Installation

This project is written in go and is released as a statically-linked binary meaning it has no dependencies.

The recommended installation method is to download the binary from the releases page.

Alternatively, build it yourself:

git clone https://github.com/tnyeanderson/sendmail-to-matrix.git
cd sendmail-to-matrix
CGO_ENABLED=0 go build .

Configuration

You must add a config file that will be used by the script, or supply a server, token, and room with command-line parameters.

Values from a config file are overwritten by command-line parameters. See sendmail-to-matrix --help for help.

NOTE: CLI options can be have a few formats, but it is recommended to use the double-hyphen syntax (--config-file instead of -config-file) for consistency with other standard applications.

First, obtain an access token:

curl -XPOST -d '{"type":"m.login.password", "user":"example", "password":"wordpass"}' "https://homeserver:8448/_matrix/client/r0/login"

Then, copy config.json.example from this repo and edit it for your needs:

cp config.json.example /app/config.json

# Don't forget to edit the file!

Note: This example places the config.json file in the /app folder. You can place it anywhere the script can read from as long as you specify it using --config-file /path/to/config.json

Your config file might look like this:

{
  "server": "https://matrix.org",
  "token": "<your_access_token>",
  "room": "!myroomid:matrix.org",
  "preface": "Sent from my homelab"
}

Ensure that sendmail-to-matrix is executable:

chmod +x /path/to/sendmail-to-matrix

Add the following line to /etc/aliases to pipe emails sent to myuser@localhost to the script:

myuser: "|/path/to/sendmail-to-matrix --config-file /app/config.json"

Note: The alias can also be added to the user's ~/.forward file.

Reload your aliases:

newaliases

Testing

To test that emails get forwarded properly, use sendmail (press CTRL+D after you have finished typing your message):

$ sendmail myuser@localhost
> Subject: THIS IS NOT A TEST
>
> A song by Bikini Kill

You should receive the following message in your Matrix room (based on the example configuration above):

Sent from my homelab
Subject: THIS IS NOT A TEST
A song by Bikini Kill

Alternatively, you can test with a file that contains an email in standard Linux mailbox form.

cat email.txt | sendmail-to-matrix

You're done! Direct any administration-related emails (Proxmox notifications, sysadmin stuff, monitoring, the works) to myuser@localhost (or whatever you created as your alias) and enjoy getting notifications in a modern way.

Caveats

• HTML tags are removed from the message body if present (and not malformed... looking at you Proxmox). multipart/alternative emails will prefer text/plain.