ietf-822
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Re: Problem with MIME and line length in Subject headers

2002-11-14 12:23:23

On 11/14/02 at 12:50 PM -0500, Keith Moore wrote:

uh, no. RFC 2822 is concerned with the user agent protocol, and it does place a few requirements on user agents. RFC 2821 is concerned with the mail transport protocol, so it places requirements on MTAs.

Well, that's true, but the rest of Charles's message was exactly right: RFC 2822 does not require (or even recommend) that user agents unfold folded headers for any reason. It simply says that for syntactic or semantic evaluation, they should be treated as if they were unfolded (e.g., if you compare to Subjects for identity, compare the unfolded form).

I don't think either 822 or 2822 is clear about the semantics of folding of header fields.

If you've got problems with 2.2.3, I'm open to suggestions. But I think 2822 is *very* clear on the semantics of folding. What it doesn't say is what (if anything) a UA should do as far as unfolding goes for presentation to the user.

but longstanding practice is that both UAs and MTAs can change the folding from that supplied by the sender.

"Can change"? Of course. But that wasn't the question that was being asked here. The question is "Should folding be changed?" It certainly shouldn't by MTAs (the "don't touch the contents of the message" maxim). It should be changed by UAs if the user has requested a very long header field that needs to be folded. Whether it should be changed to unfold a header field that is received is a trickier business. My feeling is yes, but it's at least an interesting question.

pr
--
Pete Resnick <mailto:presnick(_at_)qualcomm(_dot_)com>
QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102

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