[gweinberg]

On gmail and fastmail and maybe some other providers, you can put a plus sign before the at sign, and the plus and anything in between are stripped out so you can effectively have infinite email addresses.

Not all providers do this, but it's easy enough to check if yours does, just send an email to yourself.

[yosito]

Note, on gmail you can't filter emails based on the +

[Haegin]

I've definitely had filters set up based on this in the past. Did they change it in the last few years?

[nextos]

And some services refuse to accept these addresses.

I've found old school approaches such as https://www.spamgourmet.com/index.pl to solve this better.