Hello,

I would personally gauge the answer to this question by first asking how much do you trust the results of the Spam Assassin server? Depending on how I configure certain rules on the Spam Assassin server, I would have the limits be as low as 5 - 35. More or less depending an what else I have there. If you are testing the defaults, use that "1" for now as see how well it fairs against your expectations and adjust from there.

TLDR: It depends