Add documentation on Email

Author: XAMPPRocky

src/SUMMARY.md

@@ -2,9 +2,10 @@
 
 [Overview](./README.md)
 - [Chat Platforms](./chat/README.md)
+  - [Discord](./chat/discord.md)
+  - [Email](./chat/email.md)
   - [Zulip](./chat/zulip.md)
       - [Moderation](./chat/zulip/moderation.md)
-  - [Discord](./chat/discord.md)
 - [Core](./core/README.md)
     - [Rust Blog Guidelines](./core/blogs.md)
 - [Community](./community/README.md)

src/chat/email.md

@@ -0,0 +1,22 @@
+# Email
+
+While most of Rust's discussion happens on other platforms, email is eternal and
+we occasionally need a way to approach individuals or groups privately. Our
+email is hosted through Mailgun (provided by Mozilla). We create and edit the
+mailing lists for teams through the [rust-lang/team] repository. Our email
+domain is `rust-lang.org`, e.g. `[email protected]`.
+
+## Sending a public broadcast
+If your teams need to reach everyone in Rust organisation they can send a
+email to `all@`. It is recommended that you only use this mailing list when you
+know that you need contact every member, such as for organising a members event
+like the All Hands, or security alerts.
+
+### Keeping responses private
+When sending a message to `all@`, do not put `all@` in `To`. This will mean that
+any replies to your broadcast will also be sent to everyone. Instead put your
+team's email address in `To` field, and place `all@` in the `Bcc` field. Then
+any replies will be sent to just your team.
+
+
+[rust-lang/team]: https://github.com/rust-lang/team