We use Google Apps with our domain @serviterobotics.org to manage the email lists - in the future, we might consider switching to a more capable system that would allow individuals to manage their own subscription status, but it works well enough for now (incidentally, we switched our website domain to
www.team3309.org now that we're a Tri-school team, but we have yet to switch all of our emails to the new domain since that's a bigger hurdle).
The mass-texting idea sounds really appealing, thanks for that idea!
We also use a Facebook Group in addition to our public-facing Page, but that's more for casual discussion and posts and not for critical announcements - shockingly, there still are some students who aren't on Facebook (or aren't on often) and they would miss important information delivered that way.