I think the sendmail issues are resolved as I am now receiving updates - so try registering again. Here are the resolution comments from Ender -
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Ender - 02-19-08 05:17
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We've fixed this few days ago.

Instead of writing the information in the database with the real path, Disk Drive will also use the home symlink from now on . This way updatemedia will use the same record from database. Here is the wiki for home symlinks :
http://wiki.linuxmce.org/index.php/Home_SymlinkThe svn revision with the fix is :
http://mantis.linuxmce.org/view.php?id=19714 "