Unfortunately there is not another alternative, other than increasing the threshold for this filter in the "SFDC" tab. 

The SFDC filter works based on a "digest" (a hash) created form the email's content. Messages with very similar textual content will share the same hash. Our SFDC database collects all these hashes in realtime for every single email processed by all the SpamFilter installations in the world. When we detect a spike in any hash for which the emails are being blocked by other types of filters, our SFDC server will determine that the specific hash, at that specific time, is characteristic of a specific wave of spam that is being circulated at the moment. This will cause all emails that have that one hash to be marked as spam. As all this occurs in real-time, usually there will be a time frame of 6hr-24hr during which this spike will occur and emails with similar content will thus be blocked. There is no way to determine the specific content that is causing this to happen, as the "digest" is created statistically based on the entire contents of the email, not specific keywords or phrases.