SMTP Service Extension for 8bit-MIMEtransport (RFC1426)
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
J. Klensin: AUTHOR [+7]
This memo defines an extension to the SMTP service whereby an SMTP content body containing octets outside of the US ASCII octet range (hex 00-7F) may be relayed using SMTP.
Network Working Group J. Klensin, WG Chair
Request for Comments: 1426 United Nations University
N. Freed, Editor
Innosoft International, Inc.
Dover Beach Consulting, Inc.
Network Management Associates, Inc.
The Branch Office
SMTP Service Extension
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet
community, and requests discussion and suggestions for improvements.
Please refer to the current edition of the "IAB Official Protocol
Standards" for the standardization state and status of this protocol.
Distribution of this memo is unlimited.
This memo defines an extension to the SMTP service whereby an SMTP
content body containing octets outside of the US ASCII octet range
(hex 00-7F) may be relayed using SMTP.
Although SMTP is widely and robustly deployed, various extensions
have been requested by parts of the Internet community. In
particular, a significant portion of the Internet community wishes to
exchange messages in which the content body consists of a MIME
message  containing arbitrary octet-aligned material. This memo
uses the mechanism described in  to define an extension to the
SMTP service whereby such contents may be exchanged. Note that this
extension does NOT eliminate the possibility of an SMTP server
limiting line length; servers are free to implement this extension
but nevertheless set a line length limit no lower than 1000 octets.
3. Framework for the 8bit MIME Transport Extension
The 8bit MIME transport extension is laid out as follows:
(1) the name of the SMTP service extension defined here is
(2) the EHLO keyword value associated with the extension is
(3) no parameter is used with the 8BITMIME EHLO keyword;
(4) one optional parameter using the keyword BODY is added to
the MAIL FROM command. The value associated with this
parameter is a keyword indicating whether a 7bit message
(in strict compliance with ) or a MIME message (in
strict compliance with ) with arbitrary octet content
is being sent. The syntax of the value is as follows,
using the ABNF notation of :
body-value ::= "7BIT" / "8BI...