To reach the teen leaders, I have used texting with much success. Sometimes, if the information is lengthy, I will text a short note and ask them to read an email or go to the FB page. Most teen leaders reply quickly, IF they have your phone number in their phone.
To make it a bit easier, I use the Groups App on my iphone. It allows me to enter groups in the phone and then text them. I create the groups in my Contacts on my mac, which get shared with my iPhone and automatically loaded into the Groups text app. The app only allows batches of 10 texts at a time. I include myself on the first group, then retext the message I get to my phone to the rest of the groups of 10 persons as needed.
Is anyone else using other tools for blasting text messages to large groups?