The email market keeps growing at a steady pace and will reach nearly 5 billion users by 2024.
It was in October of 2018 that Gmail announced it had reached 1.5 billion active accounts: https://twitter.com/gmail/status/1055806807174725633
The worldwide email user market also follows suit. According to the Radicati Group, email is expected to grow to 4.4 billion unique users by 2024.
Email accounts are also expected to reach 1.86 accounts per person. I, for one, already have five (two business and three personal).