I love the Google Doc Comments feature where you can direct a comment to a user. +them@Gmail.com, etc.)
BUT it does not seem to work with non Gmail accounts (at least the email@example.com and firstname.lastname@example.org that I've tried).
I got the email but the REPLY to address is a "do not respond". But it does work in Gmail. I assume it's limited to only working (via REPLY in Gmail)?