[ptype]

I have been running this setup for years without any administration. Email forwarding tends to be included from your domain registrar so no server is necessary. You don't need a tool to generate the addresses as you can make them up as you go along.

[kazinator]

What do you mean you can just make them up as you go along?

Suppose I have two users in my domain: bob@mydomain, alice@mydomain.

How can alice just make up a new @mydomain address which goes to alice@mydomain? Okay, that part is simple: we can have an entire space of these generated by a rule, like gmail's [e-mail].

But then how does alice invalidate such an address that is misused?

I want it so that any address that is not valid generates an SMTP bounce; I don't want an infinite space of aliases that map to an address to all be considered valid, but a specific set, controlled by the user. When an element is removed from that set, then further attempts to send to it generate SMTP bounces.

Furthermore, I want it to be completely anonymized, just like Throttle are doing, as in:

   <random-chars>@mydomain -> alice@mydomain

The text "alice" doesn't appear in the plaintext anywhere, and cannot be reversed out of the local part.

EDIT:

To solve one of these problems, what we can do is assign to each user some random identifier of fixed length, from which further addresses can be generated. For instance alice@mydomain also gets "xZa3f@mydomain" when the account is created. To this local part, arbitrary characters can be appended: "xZa3f4abPspamming.dickheads.com@mydomain" such that this still routes to alice@mydomain. Doesn't handle the SMTP-level invalidation requirement though.

[ptype]

If it's my own domain (probably not unusual among the HN crowd), I would sign up to e.g. kazinator.com by 'inventing' an email address [e-mail], which is forwarded to my gmail through a catch-all email forwarding setup with my domain registrar. Emails to [e-mail] now arrives to my gmail and hence it's easy to block email (e.g. spam) arriving to this email address as well as knowing who leaked my email address to third parties.

As people have pointed out, it now seems possible to use the + functionality of gmail which I was not aware of, but the above setup avoids the issue of forms not accepting + in a valid email address.

This only works with a catch-all email forwarding as I mentioned, so if you want bounce on non-valid addresses it will not work, but like I said it has served me very well.