No, I've never received an email notification of Next Game Time changing. It is a field the GM can modify anytime, that does not generate an email. If the GM makes a post on the campaign's internal forum, the players would get a Roll20 Notification (the pink drop-down at the top right). My first suggestion, if the GM changes the Next Game time, then the GM should make a new post with clearly-written subject line, "Next Game time changed to Tuesday 8PM Eastern". Secondly if the group is friendly with each other & agrees, and everyone wants to stay on-the-same-page by email, the GM could ask for everyone's email address and send out announcements, not automatically but by taking the effort to ensure scheduling. Hope these workarounds help.
