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diff --git a/sqmail-4.3.07/man/envelopes.5 b/sqmail-4.3.07/man/envelopes.5 new file mode 100644 index 0000000..9f06ed7 --- /dev/null +++ b/sqmail-4.3.07/man/envelopes.5 @@ -0,0 +1,231 @@ +.TH s/qmail: envelopes 5 +.SH "NAME" +envelopes \- sender/recipient lists attached to messages +.SH "INTRODUCTION" +Electronic mail messages are delivered in +.IR envelopes . + +An envelope lists a +.I sender +and one or more +.IR recipients . +Usually these +envelope addresses are the same +as the addresses listed in the message header: + +.EX + (envelope) from djb to root +.br + From: djb +.br + To: root +.EE + +In more complicated situations, though, +the envelope addresses may differ from the header addresses. +.SH "ENVELOPE EXAMPLES" +When a message is delivered to +several people at different locations, +it is first photocopied +and placed into several envelopes: + +.EX + (envelope) from djb to root +.br + From: djb Copy #1 of message +.br + To: root, god@brl.mil +.EE + +.EX + (envelope) from djb to god@brl.mil +.br + From: djb Copy #2 of message +.br + To: root, god@brl.mil +.EE + +When a message is delivered +to several people at the same location, +the sender doesn't have to photocopy it. +He can instead stuff it into +one envelope with several addresses; +the recipients will make the photocopy: + +.EX + (envelope) from djb to god@brl.mil, angel@brl.mil +.br + From: djb +.br + To: god@brl.mil, angel@brl.mil, joe, frde +.EE + +Bounced mail is sent back to the envelope sender address. +The bounced mail doesn't list an envelope sender, +so bounce loops are impossible: + +.EX + (envelope) from <> to djb +.br + From: MAILER-DAEMON +.br + To: djb +.br + Subject: unknown user frde +.EE + +The recipient of a message may make another copy +and forward it in a new envelope: + +.EX + (envelope) from djb to joe +.br + From: djb Original message +.br + To: joe +.EE + +.EX + (envelope) from joe to fred +.br + From: djb Forwarded message +.br + To: joe +.EE + +A mailing list works almost the same way: + +.EX + (envelope) from djb to sos-list +.br + From: djb Original message +.br + To: sos-list +.EE + +.EX + (envelope) from sos-owner to god@brl.mil +.br + From: djb Forwarded message +.br + To: sos-list to recipient #1 +.EE + +.EX + (envelope) from sos-owner to frde +.br + From: djb Forwarded message +.br + To: sos-list to recipient #2 +.EE + +Notice that the mailing list is set up +to replace the envelope sender with something new, +.BR sos-owner . +So bounces will come back to +.BR sos-owner : + +.EX + (envelope) from <> to sos-owner +.br + From: MAILER-DAEMON +.br + To: sos-owner +.br + Subject: unknown user frde +.EE + +It's a good idea to set up an extra address, +.BR sos-owner , +like this: +the original envelope sender (\fBdjb\fP) +has no way to fix bad +.B sos-list +addresses, +and of course bounces must not be sent to +.B sos-list +itself. +.SH "HOW ENVELOPE ADDRESSES ARE STORED" +Envelope sender and envelope recipient addresses +are transmitted and recorded in several ways. + +When a user injects mail through +.BR qmail-inject , +he can supply a +.B Return-Path +line or a +.B \-f +option for the envelope sender; +by default the envelope sender is his login name. +The envelope recipient addresses can be taken +from the command line or from various header fields, +depending on the options to +.BR qmail-inject . +Similar comments apply to +.BR sendmail . + +When a message is transferred from one machine to another through SMTP, +the envelope sender is given in a +.B MAIL FROM +command, +the envelope recipients are given in +.B RCPT TO +commands, +and the message is supplied separately by a +.B DATA +command. + +When a message is delivered by +.B qmail +to a single local recipient, +.B qmail-local +records the recipient in +.B Delivered-To +and the envelope sender in +.BR Return-Path . +It uses +.B Delivered-To +to detect mail forwarding loops. + +.B sendmail +normally records the envelope sender in +.BR Return-Path . +It does not record envelope recipient addresses, +on the theory that they are redundant: +you received the mail, +so you must have been one of the envelope recipients. + +Note that, +if the header doesn't have any recipient addresses, +.B sendmail +will move envelope recipient addresses back into the header. +This situation occurs if all addresses were originally listed as +.BR Bcc , +since +.B Bcc +is automatically removed. +When +.B sendmail +sees this, it creates a new +.B Apparently-To +header field with the envelope recipient addresses. +This has the strange effect that each blind-carbon-copy recipient will see +a list of all recipients on the same machine. + +When a message is stored in +.B mbox +format, +the envelope sender is recorded at the top of the message +as a UUCP-style +.B From +(no colon) line. +Note that this line is less reliable than the +.B Return-Path +line added by +.B qmail-local +or +.B sendmail\fP. +.SH "SEE ALSO" +qmail-header(5), +qmail-local(8), +qmail-inject(8) |