Someone was recently asking about contacting other members directly and it reminded me of this thread.
Our Photosynth profiles have RSS feeds on them (four of them, actually, and one is for comments on your own synths). If you add the RSS feeds for your profile to an RSS aggregator of your choice it should be as good as being emailed when your synths or panos get new comments.
(Most web browsers have RSS readers built in nowadays and may file them under 'Feeds' 'Live Bookmarks' or something similar, or if you use the Windows Live Mail desktop program it has RSS feed support, you could use the RSS widget for Windows Vista Sidebar or Windows 7 desktop, Google News Reader online, etc. etc.)
Just be sure to use an RSS reader which you will open as often as your email - ideally it will actually be in your email program or website.