グレーのバックは、後発のRFCにより廃棄されたことを示す。

(原典:rfc-index.txt, std-index.txt

STD0010 : Simple Mail Transfer Protocol
RFC0821 Simple Mail Transfer Protocol J. Postel Obsoletes RFC0788
Obsoleted by RFC2821
Aug-01-1982 TXT=124482 bytes STANDARD
RFC1869 SMTP Service Extensions J. Klensin
N. Freed
M. Rose
E. Stefferud
D. Crocker
Obsoletes RFC1651
Obsoleted by RFC2821
November 1995 TXT=23299 bytes STANDARD
RFC0974 Mail routing and the domain system C. Partridge Obsoleted by RFC2821
Jan-01-1986 TXT=18581 bytes HISTORIC
RFC0788 Simple Mail Transfer Protocol J. Postel Obsoletes RFC0780
Obsoleted by RFC0821
Nov-01-1981 TXT=109001 bytes UNKNOWN
RFC0780 Mail Transfer Protocol S. Sluizer
J. Postel
Obsoletes RFC0772
Obsoleted by RFC0788
May-01-1981 TXT=80352 bytes UNKNOWN
RFC0772 Mail Transfer Protocol S. Sluizer
J. Postel
Obsoleted by RFC0780
Sep-01-1980 TXT=61061 bytes UNKNOWN
RFC1651 SMTP Service Extensions J. Klensin
N. Freed
M. Rose
E. Stefferud
D. Crocker
Obsoletes RFC1425
Obsoleted by RFC1869
July 1994 TXT=22153 bytes DRAFT STANDARD
RFC1425 SMTP Service Extensions J. Klensin
WG Chair
N. Freed
M. Rose
E. Stefferud
D. Crocker
Obsoleted by RFC1651
February 1993 TXT=20932 bytes PROPOSED STANDARD
RFC2821 Simple Mail Transfer Protocol J. Klensin Obsoletes RFC0821
RFC0974
RFC1869
April 2001 TXT=192504 bytes PROPOSED STANDARD