Considering just what a bloated piece of...
...shite the Notes client was when I used it (R5) - I'm not surprised they couldn't port it to Linux.
As the [link|http://www.iarchitect.com/lotus.htm|Interface Hall of Shame] states about 4.6, "We wish we found IBM's Lotus Notes a long time ago. This single application could have formed the basis for the entire site. The interface is so problematic, one might reasonably conclude that the designers had previously visited this site, and misread "Hall of Shame" as "Hall of Fame". Lotus Notes 4.6 contains almost every example of inefficient design illustrated thoughout the entire Hall of Shame site."
R5 didn't seem to be much of an improvement over 4.6 - slow, buggy, and horrible - and that's just the e-mail package.
One of these days, I'll have to sit down and figure out why people use it. It probably has to do with the server, because I can't see an ounce of value in the client.
