Want to contact me? You can e-mail me.
I have a PGP public key if you're the sort to ask for one.
I think e-mail is the best online communication medium because it's the one people are most likely to have.
More people use e-mail than [insert other service here]. In fact, [insert other service here] likely requires its users to have e-mail addresses.
E-mail is also decentralized and has open standards, leading to the wide availability of e-mail providers and clients.