Some time after upgrading to Ubuntu 11.10 I ended up with the dreaded “Unable to retrieve message” in Evolution (which I use for Exchange connectivity). This has usually corrected itself by simply restarting Evolution, but this time nothing would help. I stumbled across a thread that provided a few ways to possibly solve the issue, but the .evolution directory didn’t contain any live installation in Ubuntu.
Turns out the directory is:
.local/share/evolution
As both my mailstore and address book lives on the Exchange server, I decided to just move the evolution directory to a new name and recreate the evolution directory from scratch. This takes a bit of time while Evolution indexes everything, but after a while everything were back to normal.