[sumodm]

First point is really important. I can give email addresses to 100 people in India and ask them to message an important medical information (something of high value to recipient and no value to this person, at negligible effort) and the conversion would be quite low. Email for unacquainted users is perceived to be hard. Large part of India and other developing countries became digital without going through the internet of 90s and early 2000s. So email is foreign to large mass of people.