I'll have to check and see why kmail has that as the default. enabling RBL'sdoesn't have to query them everytime does it? meaning does it cache them.
No, SA doesn't cache them, and does test them every time. Running a caching DNS server somewhere near the SA machine (possibly on the same machine) is a good idea. It depends on your mail load. If this is a personal-use machine the cache probably isn't needed.
Loren
