I have the same problem.
After installing 'evolution-plugins-experimental', ensuring 'tnef-
attachment' is enabled, and restarting machine, "winmail.dat"
attachments are not recognised.
I have updated all packages via 'apt-get upgrade'. dpkg -l evolution\*
yields:
Desired=Unknown/Install/Remove/
I experience the same hang on Karmic, using an IMAP account. It seems
this bug has not been reviewed since 2007-12-10.
--
Evolution hangs with "Formatting Message" after several hours
https://bugs.launchpad.net/bugs/175233
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Desk