According to the RFC ‘+’ is a valid character and tagged addresses (which aren’t mentioned) represent unique users (so removing the marker could result in the email not being delivered at all.)
Though similarly, email usernames ('local part') are case sensitive but I've never encountered a mail server where this was the case. I imagine if a nefarious party stripped the markers, they'd lose the tiniest percentage of their audience that way.
(Aside: Your own approach to using + is quite clever as it's the total opposite to most users, so you'll see who pulls this trick ;-))
Though similarly, email usernames ('local part') are case sensitive but I've never encountered a mail server where this was the case. I imagine if a nefarious party stripped the markers, they'd lose the tiniest percentage of their audience that way.
(Aside: Your own approach to using + is quite clever as it's the total opposite to most users, so you'll see who pulls this trick ;-))