28 years later and people are still trying to reinvent LISTSRV
If you want to be maximally inclusive, an email based system is the way to go. Everyone has email, it's compatible with every smartphone, feature-phone, Blackberry, PC, Mac, etc., it's generally not limited by corporate firewalls, and savvy users have a huge amount of control over filtering, notifications, etc. Yahoo and Google groups make setting up a free email list absolutely trivial.