What is RFC821?
A Request For Comments (RFC) document defines a protocol or policy used on the Internet. An RFC can be submitted by anyone. Eventually, if it gains enough interest, it may evolve into an Internet Standard. Each RFC is designated by an RFC number. Once published, an RFC never changes. Modifications to an original RFC are assigned a new RFC number.
The following link will display the entire contents of RFC821 Keywords:SMTP RFC RFC821 821
RFC821 (Simple Mail Transfer Protocol)
Keywords:SMTP RFC RFC821 821