If you are using spamassassin without sa-update you will not like to hear that as of 5 days ago spamassassin has pretty much declared open season on all your mails:

Due to an incredibly gross and dirty bit of rule all properly dated mails get an extra 3.6 added to their score. kablam!

Botch/Fix: edit /usr/share/spamassassin/72_active.cf, and change the regexp for FH_DATE_PAST_20XX to something that doesn't fire in the near future (like 20[2-9][0-9]). Don't forget to sa-compile if you use compiled spamassassin rules.