ietf-822
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Re: questions on RFC2822

2001-09-10 12:17:45

On 9/10/01 at 1:17 PM -0500, Eric A. Hall wrote:

1) There does not appear to be a requirement for a space after the colon in the header field...

That is correct. Though a space definitely makes it more readable and lots of clients produce the space, it is not required at all, I've seen messages without, and I've never seen anybody fail to parse a header without a space.

2) Although any printable character from US-ASCII except colon may be used in header names, I've never seen any headers use anything other than alphanumerics and hyphen.

I've never seen one that I can recall. Anyone else?

3) There is no explicit length limit on field names.

Correct. You only have to stay with in the line length limit.

...particularly since usefor-05 says that some of the field body must appear on the same line as the field name.

Usefor is a particular profile of 2822 since evidently newsreaders have problems parsing all of 2822. It is silly to implement folding/unfolding and not be able to handle it on the first line, but it's fine if usefor wants to impose stricter limitations. They do not apply to mail.

On the flip side, there is nothing in 2822 that requires making ridiculously long header names.

4) There is no explicit length limit on an unfolded header field...My assumption is that the friendliest behavior is to endeavor to keep folded parts at 78 bytes...

Absolutely. That follows the 78 recommendation.

...with the entire unfolded header field within 998 bytes.

I've met many an address field that is well over 998 bytes unfolded. Parsing much larger fields is a necessity for any implementation. There is no need to stick to 998 for unfolded field length.

5) String length in header bodies is similarly undefined.

As above.

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

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