SimpleLogin is self hostable as aura- mentioned below.
I use simple login and think it's great.
Another self-hostable option is AnonAddy https://github.com/anonaddy/anonaddy
I use anonaddy [0] because it's open source and self-hostable [1]. I don't have to worry about the service going under or jumping the shark, since I can always just self-host it on my own hardware and import my config should that happen. Of course I'd much prefer to pay someone else to run it, especially in the case of mail servers where self-hosting is notoriously tedious.
[0] https://anonaddy.com/ [1] https://github.com/anonaddy/anonaddy
Check AnonAddy, it does exactly what you want and it is open source too [0]. You can self host or use their paid service at $1/month. They also did a Show HN thread when it was launched [1]
For those who do not wish to interact with their webserver config (or can't) there is AnonAddy, which can be self-hosted (https://github.com/anonaddy/anonaddy) or paid for (https://anonaddy.com/). It's really convenient, with the added benefit (for the paid version) of having a domain, that is used by many people, which makes it easier to hide behind an email address.
The most popular open-source alternatives are SimpleLogin[1] and AnonAddy[2]. The former one was just acquired by ProtonMail[3].
[1] https://github.com/simple-login/app/
[2] https://github.com/anonaddy/anonaddy
[3] https://protonmail.com/blog/proton-and-simplelogin-join-forc...