Before this start to be a FAQ:
If you upgrade from FreeBSD 5.1 to 5.2, please do
portupgrade -Rf 'exim-*'
Otherwise your symptoms may include entries in /var/log/exim/mainlog like:
spool directory space check failed: space=0 inodes=0
This may be caused by the changes in the statfs structure,
see entry 20031112 in /usr/src/UPDATING:
<
http://cvsweb.freebsd.org/src/UPDATING?rev=1.282>
Regards
Oliver