It most definitely is. Reason been is that you will receive 30 VP's for sending them mail once a week and the another is that you never know when they will become active. Some may take weeks or months before they actually decide to start working their SFI business. I have had a few that just signed up and never bothered doing any task's at all. Then suddenly they started working.
So I definitely think it is worth sending them motivational mail every week.
All the best to you
