I was thinking, would it be feasible to have an option for spamassassin to exit after a message reached the spam threshold?
That was a feature, in SA 2.1.x if I recall correctly.
The problem with that is to do it right SA must make sure to run all the negative-scoring rules first, otherwise a message might wind up being a false positive. (The old SA version with this feature had FP problems).
Forcing the negative scoring rules first was tried, but this generally forced SA to make two passes over the message body, making all the performance gains of exiting early entirely moot.
