Seriously considering unleashing hell upon Lotus for making such a crappy e-mail client.. I work at a business school where pretty much everyone except me uses Notes. It seems amazing that mail gets delivered at all..
It definitely shows it's heritage as a `groupware' system, not designed at all to communicate over the Internet.. Hell, it doesn't even have message threading, and no messages ever have In-Reply-To (or similar) set in the headers.. Really sad..
Personally, I had thought that an XML format for e-mail might be kind of cool (if it was well thought out, and there were good mailers/interpreters both on the text console end and the GUI side of things). Looks like some of the big names got together and created one back in 1998. Of course, I don't think anyone is using it...