Re: Update to RFC 5322 to allow "group" syntax in the "from" header

On Mon, 2012-09-10, Barry Leiba wrote:

> I have this change queued up:

> OLD
>    If the from field contains more than one address (mailbox or group) in the
>    address-list, then the sender field, containing the field name "Sender" and a
>    single mailbox or group specification, MUST appear in the message.

> NEW
>    If the from field contains more than one address (mailbox or group) in the
>    address-list, then the sender field, containing the field name "Sender" and a
>    single mailbox or group specification that refers to no more than
> one mailbox,
>    MUST appear in the message.


Does this mean that an empty group counts as one "addr-spec" for 
the purposes of requiring a Sender: field?

If not, it sounds to me as if an IMAP or POP server downgrading for a 
legacy client will have to "violate" this rule since a downgraded 
From: field will normally have only an empty group with the 
UTF8 addr-spec hidden in the name of the group. If that triggers 
the requirement for the server to create a Sender: field, the only 
thing available to put into it is the same empty group in the 
From: field.

My belief is that the downgrading process in this case can just 
leave the From: field with an empty group and presume that the 
client will not crash on the missing Sender: field.

Note that the damage will not likely propagate since the message
is unreplyable!

-- 
Bill McQuillan <[email protected]>

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