I agree which is why I’ve started an email client module.
I’ve lost track with appointment reminders with email but may have to do with MedEx or batch communications tool in mics menu. The Batch Tool seems nice but unsure it works any longer.
Still if you want to send email appointment notification you can use my module. I still have to do some core integration for other functionalities but I hoped other vendors would pick up and donate back some core integrations by way of events. I just don’t have time to finish and follow through on a lot of the features I bring in but always give the ability for others to pick up and carry on the projects.
Anyway you can send reminders with this: Newly Improved Fax, SMS and Email Module