the notification should come from genealogy AT isleofman.com
with subject line starting:
[Manx Genealogy:] Re: ...
you did give a valid email address on registering didn't you ? (all too often I find people misquote their email or forget that they have changed it)
do you have access to rejected mail (if so check in the spam folder) or have you set up some form of whitelist - I found many AOL users had inadvertently set up to reject any email from those they had not sent an email to (stops them for example getting a reply from me to any post via my manxnotebook address