I think this works in practice but I still prefer to have an anonymous/hidden/random email for each service. If one of your Gmail alias emails is sold, isn’t it trivial to write a script and figure out the real Gmail addresses?
Fair. Feels like it’s an uncommon enough practice that most marketers don’t bother. I had access to a 6,000,000+ email list one time and I was curious how many people did this trick and it was under 100.
