Scott Gifford <sgifford(_at_)tir(_dot_)com>:
I think that there is enough ambiguity in the definition of the Sender
header, and enough mail clients that feel that putting something that
identifies the sender but isn't a legal email address is the right
thing to do, that an option to ignore Sender: would be reasonable and
useful.
A literal reading of RFC822 sec. 4.4.2 supports the idea that Sender:
doesn't have to be a working email address...
The definition of the Sender header in RFC822 says, in part, "The
Sender mailbox specification includes a word sequence which must
correspond to a specific agent (i.e., a human user or a computer
program) rather than a standard address." That implies that the
contents of the Sender field don't need to be a legal email address at
all.
It also says "This field contains the authenticated identity of the
AGENT (person, system or process) that sends the message." Based on
this, Netscape's behavior is reasonable; to use the user-supplied
address would be using an identity which is not authenticated. If
Netscape is following the rules, it seems that fetchmail should do its
best to make the right thing happen, or at least make it possible to
make the right thing happen.
Seemingly contradicting the above, later (in sec. 4.4.4), the RFC
says:
o The "Sender" field mailbox should be sent notices of
any problems in transport or delivery of the original
messages. If there is no "Sender" field, then the
"From" field mailbox should be used.
which implies that it should be a legitimate address.
It appears that the relevant standards aren't very clear on this, and
a client that puts weird crap into the Sender header isn't really all
that out-of-line. Supporting both behaviors doesn't sound like an
unreasonable thing to do, especially with a patch in hand.
RFC2822 is clear on this. The Sender field must be a legal mailbox address.
Eric, if Jonas made this into a configurable option, would you
consider incorporating his patch?
I'm very resistant to adding options. Instead, I've added a simple
adaptation for 5.8.3 -- Sender and Resent-Sender headers are ignored
if they don't contain an @. This should do as an ersatz for testing
whether the field contains a legal address.
--
<a href="http://www.tuxedo.org/~esr/";>Eric S. Raymond</a>
The whole aim of practical politics is to keep the populace alarmed (and
hence clamorous to be led to safety) by menacing it with an endless series
of hobgoblins, all of them imaginary.
-- H.L. Mencken