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rfc822: Can anyone explain multiple mailboxes?

In article <4635t9$>,
Ian Sheldon <> wrote:
>I am trying to understand RFC822, but I am confused by
>the ``multiple mailboxes'' section since my mailer doesn't
>appear to support it (editing a mailbox to include

Many user agents don't, unfortunately.  And some transport agents
that take it into their heads to mess with header lines screw up
group addresses.

>So, for example, if the reply-to address consists of
>  Reply-to: Mygroup:;
>then who exactly would get the reply?   Presumably, Mygroup
>should be in the /etc/aliases (or equivalent)?

No, no.  The "phrase" part of a group address is just that.  It is
not itself an address, and has no semantics.

If you want to use group syntax in a `Reply-To:' field, it is
meaningless (although apparently legal) to omit the members of the
group.  This facility is only useful in "destination" fields (`To:'
and friends).

I occasionally use it when I need to send a one off message to
several dozen people, or I need to send a message to several people
without each one knowing who all the other recipients are (of
course, `BCC:' can also be used for the latter case).  I would type
into my user agent something like this.

    To: Some friends:,,
             Uncle Tom Cobbley <>;

My user agent extracts the three addresses from the group to give
to the transport agent, then rewrites the field to this.

    To: Some friends:;

>                                                And, if
>the mail is sent externally, presumably the mailer is
>responsible for filling in the other recipients (i.e.
>expanding Mygroup:; to MyGroup:user1,user2,user3;)?

No.  Again, the "phrase" part cannot be used to identify the members
of the group.  Once a message with a `To:' line like the above has
been submitted, the addresses only exist in the envelope, and can
never be restored to the header.

>If the reply is Mygroup:user1,user2; then presumably
>user1,user2 would get the reply


>                                and the contents
>of MyGroup alias in any file would be ignored?

They would be ignored in any case.

>I'd be grateful if anyone could confirm whether or not I've
>understood it correctly.

Section 6.2.6 of RFC 822 is rather confusing---make sure you
understand the distinction between an "address" and a "mailbox".
The comment "(i.e. a distribution list)" should be omitted IMHO,
since what is usually meant by a distribution list is described in
the last paragraph: "a single mailbox reference [which expands] to
the full distribution list".

Tim Goodwin   | "... which works fine, but from a language design aesthetics
Unipalm PIPEX | point of view (i.e., mine), is grotesque." -- Chris Torek

Original headers:

From: (Tim Goodwin)
Newsgroups: comp.mail.headers
Subject: Re: rfc822:  Can anyone explain multiple mailboxes?
Date: 19 Oct 1995 12:29:01 GMT
Organization: Unipalm PIPEX
Message-ID: <465gad$>
References: <4635t9$>

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