Masking your WordPress install is a pretty good idea for plenty of other reasons though, just hiding wp-login will save you a lot of headache with bots wasting your CPU cycles and bandwidth trying to bruteforce.
Sounds like a challenge to hide the wordpressyness entirely though, it's got a huge surface area.
I also get these emails but run a WordPress site. I was convinced they would fingerprint websites and mail those to these sites only.
It was on my todo to see if I could hide the fingerprint of WordPress.
But now that you mention this, it's obvious it wouldn't do much. In hindsight, I could have know these spammer would just spam everybody in bulk.