Technology has changed and twitter DM's are becoming the new emails because people perceive they are personal and not generated but they can be. New software for coaches has DM's as an option along with snapchat and instagram. The newest is a snapchat from practice with a note inviting them to a camp. No one assumes you can mass generate snapchats but you can through the newer recruiting software.
PitchingFan: Not trying to challenge you; just curious-- What do you base the above on re: mass targeting for Twitter DMs and Snapchat/Instagram messages? Maybe you work in a related industry or have an article link you could share? It makes sense that someone would develop the ability to target these media, since there are $$ to be made. I just hadn't heard of DMs as targeted marketing, at least not for users as small as college baseball camps. (I also don't use social media much at all...)