I am moving my site to WP-Engine and they don't host email. I assume there is no problem keeping email on my existing server since that works fine, and just making sure MX records point there, but I wanted to make sure. I also use this plugin - https://wordpress.org/plugins/buddypress-group-email-subscription/ - but I assume if BuddyPress works this will too. I just want to make sure I am not overlooking something obvious. The email would stay on a VPS server with HostGator.