[mceachen]

If you're using gmail, plus-suffixing is a low-effort but effective countermeasure: [e-mail] gets delivered to [e-mail].

[hinkley]

I have about a 20% failure rate where email address validation fields reject the + character

[gingerlime]

and knowing it's gmail, it's trivial now for the company to simply drop the +... part and store/use your real email address.

[mceachen]

Ah. You can set up dash-suffixing if you're using a custom domain with gmail. Create a new "catch-all" email account. Log into that new catch-all account, and create forwarding rules for alice-* to go to [e-mail], bob-* to go to [e-mail], ...

I've done this for more than a decade.