[account42]

> I receive a Newsletter from a company I never heard of → <company name>@example.org sold my email address (and they can't strip the marker off, which they easily could with the +suffix).

This isn't reliable as true catch-all adresses (i.e. any local part works) are easily detected at which point spammers can just use whatever. I also don't find this too useful because usually you either can't afford to stop doing business with the company (in which case you get to be angry but can't take any real action) or you could have just used a temporary address in the first place.

[marssaxman]

> true catch-all adresses (i.e. any local part works) are easily detected

This may be true in theory, but in practice, on my domain at least, it has never happened.