I prefer the SFI messaging system for the simple fact that I know my mail will not get sent to the spam folder. With that being said it's also depends on how often your emailing them and how long the message is. SFI does limit those things but the limit is set very high so the average person usually doesn't have to worry about it. I do keep a list of my downlines email address though just to be on the safe side and some affiliates prefer to talk through their personal email rather than SFI.
