The word "uuencode" is derived from "Unix to Unix encoding." A uuencode message can be identified when the first word in the message is "begin." The following is an example of a uuencode message:
begin 664 sampleletter.txt
begin <mode> <file name>
<mode> = the file's read/write/execute permissions as three octal digits
<file> = output name to write the decoded data
The MIME Version 1.0 header usually identifies that a message is a MIME message and that the message complies with RFC 2045. The following is an example of a MIME Version 1.0 header:
Mime-Version: 1.0
"MIME-Version" ":" 1*DIGIT "." 1*DIGIT
Both standards (MIME and uuencode) cannot be combined in the same message as displayed in the following sample header:
Date: Fri, 2 Dec 2005 14:21:33 +1100 (EDT)
From: John Doe <JohnDoe@contoso.com>
Message-Id: <200512020321.server.domain.com>
To: Jane Doe@contoso.com
Subject: View the attachment
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Return-Path: JohnDoe@contoso.com
X-OriginalArrivalTime: 02 Dec 2005 03:21:31.0901 (UTC)
FILETIME=[7DDA6AD0:01C5F6EF]
Here is your attachment report
begin 664 sampleletter.txt
M:6-L;W)P+G`@92L@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@
M("`@(#,N-BXV($EN=F5N=&]R>2!$971A:6P@8GD@3&]C871I;VX@("`@("`@
M("`@("`@("`@("`@("`@("`@("`@("`@("`@($1A=&4Z(#`R+S$R+S`U#0I0
M86P-"E-I=&4@("`@($QO8V%T:6]N($ET96T@3G5M8F5R("`@("`@("!2968@
M("`@("`@("`@("`@("`@54T@(%%T>2!/;B!(86YD($-R96%T960@($5X<&ER
M92`@($%S<V%Y("4@1W)A9&4@4W1A='5S("`@079A:6P@3F5T($]V<DES#0H
M
M+2TM+2TM+2`M+2TM+2TM+2`M+2TM+2TM+2TM+2TM+2TM+2T@+2TM+2
TM+2TM
M+2TM+2TM+2TM("TM("TM+2TM+2TM+2TM+2`M+2TM+2TM+2`M+2TM+2T
M+2`
M
M+2TM+2TM("TM+2TM("TM+2TM+2TM("TM+2TM("TM+2`M+2TM+0T*,C`P,"
`@
M("`@1C`P,2`@("`@,3`P,#`@("`@("`@("`@("`@("`@("`@("`@("`@("`@
M("`@("!%02`@("`@("`@+3$X+C`@,#(O,#<O,#`@("`@("`@("`@("`P+C`P
=("`@("`@("`@("`@("`@($)A=&-H($E$.@T*#!H@
`
end