Yeah I know about that trick. I’ve run into problems using that in the past because the + notation isn’t universally supported, and also some companies sell their customer lists to other companies. I forget the specific details because it happened years ago now, but I found one of my + addresses signed up to a mailing list I didn’t want to be on. The form used to unsubscribe from that list considered the + an invalid character, so I couldn’t unsubscribe. As I recall it took a week or so of emails to various contacts at that company to get me unsubscribed.

Besides, it wouldn’t help at all in this particular case. Look at the screenshot. It’s redacting everything in the email address before the @, so I still wouldn’t know which one they are referring to.