This is not about a problem with the current text, but rather a bit of
confusion started by RFC 733 that might benefit from some clarifying language.
I see the confusion rear its head regularly and think it time to have some
text that tries to help people understand the difference between information
and its encoding...
> 3.6.2. Originator fields
> The originator fields indicate the mailbox(es) of the source of the
> message. The "From:" field specifies the author(s) of the message,
> that is, the mailbox(es) of the person(s) or system(s) responsible
> for the writing of the message. The "Sender:" field specifies the
> mailbox of the agent responsible for the actual transmission of the
> message. For example, if a secretary were to send a message for
> another person, the mailbox of the secretary would appear in the
> "Sender:" field and the mailbox of the actual author would appear in
> the "From:" field. If the originator of the message can be indicated
> by a single mailbox and the author and transmitter are identical, the
> "Sender:" field SHOULD NOT be used. Otherwise, both fields SHOULD
Add after this:
Note: The Sender (responsible agent) information is always present. The
absence of the "Sender:" field merely means that the information is redundant
with the "From:" field, so it is not redundantly encoded into a separate
field. The absence of the "Sender:" field sometimes confuses readers into
believing that the Sender responsible agent information has not been specified
Seems like a reasonable clarification to me.