Ask HN: Good throw-away email service?

Signing up somewhere, I often find myself wishing for an email that:

1. I can create instantly (as many as I want)

2. Will forward to my real email

3. Can be turned off later

4. Won't expire until I turn it off

Most temporary email services give you an expiring inbox that self-destructs after X hours. But I want to control the destruction myself.

Any recommendations for services or libraries for building this myself against my own domain?