Today there are over 8,500 RFCs whose publication is managed through a formal process by the RFC Editor team.

How many RFCs have there been for email?

Today, more than 8500 RFCs have been published, ranging across best practice information, experimental protocols, informational material, and, of course, Internet standards.

What are the other four RFCs that updates the initial RFCs?

Streams. There are four streams of RFCs: IETF, IRTF, IAB, and independent submission.