One of our clients was having a problem with email messages sent from a colleague’s Blackberry always ending up in her spam folder.

To resolve this, we added Blackberry’s IP address ranges to our spam filter’s whitelist IPs.  Here are the IP address ranges to allow:

206.51.26.1-206.51.26.255
193.109.81.1-193.109.81.255
204.187.87.1-204.187.87.255
216.9.248.48-216.9.248.52

That seems to be a comprehensive list.