I couldn't find anything in Bugzilla, so was hoping someone could confirm/deny whether they're seeing this buggy behavior too. I see it on the Demo accounts even.
Use case: user wants to forward only mail without attachments
Setup: user sets up filter with Attachment does not exist as the condition and Forward to as the action.
Observed: SaveRulesRequest is sent that contains <c name="not attachment"/>, but the filter doesn't act that way and subsequent GetResultRequest returns a rule that is checking does exist.
Seems like the "not" doesn't work with "attachment" despite UI offering it ?