As this subject has come up a number of times among those that have seen this site or been made aware that such a domain is taken/in use I will address it here.
Due to security concerns and technical feasibility, I do not allow email addresses in any of the domains I have registered: isolation.net or crepuscular.net. To allow access to email in these domains to others that don't actually live with me (which is everybody) would require me, at the very least, to enable IMAP and a web-based server for access outside of my firewall. Since I tend to be lazy these days regarding the configuring of such tools I'm not inclined to set this up. The other option would be to open my firewall to POP3 or IMAP access - an option that is right out for obvious reasons.
Another problem is that my bandwidth at home is quite severely limited by the laws of ADSL service and I'm not made of money, so a T1 is not on the 'Gotta Get' list for any upcoming year in the near future.
I'm sorry to be such a downer to those that would like an email address, particularly in the isolation.net domain, but them's the rules and they aren't likely to change anytime soon.