@lain @kaia @smug they should not do it because by the standard, anything before the @ symbol is opaque to the sender, and + is just a convention (X.511 uses a complex slash system) of course that doesn't matter at all in the real world. I use the catchall because a lot of systems now refuse emails with a + in the name because they're rats.

My grandfather used this trick before I was born to catch who was sending him junk mail. Whenever he signed up for anything he used a different middle name and he kept it in a notebook. Then when he got junk mail he knew who sold his name.