Comment 41 for bug 338982

I see this issue. We have clustered exchange servers, and I know libmapi have problems with them. Might be related.

http://mailman.openchange.org/pipermail/devel/2008-May/000691.html

according to the svn log they have implemented support for this kind of redirection (not long ago so I don't know how good it is working, havent had time to test it)