What's frustrating is that very many sites know of this method and simply trim the "+uniqueid" from a gmail.com address before inserting it into their database.
So, instead of doing johndoe+hn@example.com, I can do hn@example.com.
Fastmail has an interesting variation of this that supports multiple users on the same domain: hn@johndoe.example.com. My wife and I both use that feature heavily on our domain.
Unfortunately, there is a mathematical theorem (greater idiot theorem) that makes it technically impossible to generate a new random string that becomes an inbox that goes to your inbox.
How do I know that it's technically impossible?
Because otherwise Gmail would have done it already, since this takes 20 minutes and fixes a glaring security issue that gives spammers access to your email that you didn't grant.
I can't have an IQ 50 points higher than all Gmail engineers, so it must stand to reason that I'm the greater idiot. Hence there must be something preventing this obvious solution. QED.
so for sure it isn't possible for some reason, even if someone else is doing it.
what other explanation can there be? why would they just have a glaring security hole like that, allowing anyone you try to give a trackable email to with + to just remove it with a regex? It doesn't make sense. there must be some reason it can't work.
The + need not have been intended as a spam filter; I use it for bona fide filtering of separate clients’ projects.