In my experience we send "email" type communication almost exclusively by Facebook messaging. I have never in my life written or received an email from someone

In my experience we send "email" type communication almost exclusively by Facebook messaging. I have never in my life written or received an email from someone in my age bracket intended to communicate. When my classmates and I use email, it is to share attachments or to communicate with adults. iMessage is just slightly nicer SMS. Very common in Apple-heavy social groups and not that useful in others.