Answer in 200 words excluding questions 8.1 What is the difference between RFC 5321 and RFC 5322? 8.2 What are the SMTP and MIME standards? 8.3 What is the difference between a MIME content type and a MIME transfer encoding? 8.4 Briefly explain base64 encoding. 8.5 Why is base64 conversion useful for an e-mail application? 8.6 What is S/MIME? 8.7 What are the four principal services provided by S/MIME? 8.8 What is the utility of a detached signature? 8.9 What is DKIM?