Here's a form with which you can email me. Please be sure to input your actual email address and/or provide other valid contact info if you require a response.
If your message has file attachments or you'd just prefer to email me directly, send your email to rob at this domain.
If you wish to use GPG/PGP encryption, my public key can be found here.
If you wish to get in touch by means other than email, here are some more ways to contact me.