In broad strokes, here's a summary of what Heimdall does:

• Heimdall is a self-hosted email alias/forwarding service
• It's a self-hosted and self-managed service, you have complete control over your data

It allows you to:
1. Receive safely: Receive emails on single-use aliases and forward them to your personal inbox.
2. Reply anonymously: Reply to emails from your alias without revealing your personal email address.
3. Attachments: Attachments are supported on incoming and outgoing emails (subject to size limits - see below).
4. Email commands: Manage your aliases through email directly - no separate app or website required.
5. Usage stats: Easily check the usage stats of each alias.

Disclaimer: I have nothing to do with this project. I read the article and wanted to know what you think of it.