Sending out an unsolicited text message is just that "spam". Probably illegal, at least can be obtrusive. If you're OK with receiving updates or whatever, then there is approval and therefore they cannot be considered "unsolicited". I received one from a SP mentioning she was available or back or something to that effect, but the encounter with her was far from noteworthy. At least for me anyways. Considering I rarely see SP's getting a message from her is a dangerously high ratio and could be destructive to a more active hobbiest than myself.