I use SPF from a slicehost IP for membership confirmations, more-than daily mailings to most members, and occasional announcements. No reported failures yet an

I use SPF from a slicehost IP for membership confirmations, more-than daily mailings to most members, and occasional announcements. No reported failures yet and all my tests have worked. I figured hitting a large percentage was enough. When volumes get high enough, I'll worry about what could only be a very small percent of failures.