RFC 2047, "MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text", November 1996Source of RFC: 822ext (app)
Errata ID: 3749
Publication Format(s) : TEXT
Reported By: Alec H. Peterson
Date Reported: 2013-10-11
Rejected by: Barry Leiba
Date Rejected: 2013-10-26
Section 2 says:
An 'encoded-word' may not be more than 75 characters long, including 'charset', 'encoding', 'encoded-text', and delimiters. If it is desirable to encode more text than will fit in an 'encoded-word' of 75 characters, multiple 'encoded-word's (separated by CRLF SPACE) may be used.
It should say:
An 'encoded-word' may not be more than 75 characters long, including 'charset', 'encoding', 'encoded-text', and delimiters. If it is desirable to encode more text than will fit in an 'encoded-word' of 75 characters, multiple 'encoded-word's (separated by CRLF SPACE) may be used. Multiple encoded words MAY exist on a single line, in that event a SPACE MUST separate the encoded words, and after decoding the SPACE is not rendered.
Section 2 makes no mention of multiple encoded words per line, or how to handle it. However, the example at the end specifically illustrates what should happen (section 8)
(=?ISO-8859-1?Q?a?= =?ISO-8859-2?Q?_b?=) (a b)
In order to cause a SPACE to be displayed between two strings
of encoded text, the SPACE MAY be encoded as part of one of
I think I just hadn't fully digested the whole RFC. I was just re-reading the RFC in working to come up with the proposed change, and then I saw this in section 6.2:
When displaying a particular header field that contains multiple
'encoded-word's, any 'linear-white-space' that separates a pair of
adjacent 'encoded-word's is ignored. (This is to allow the use of
multiple 'encoded-word's to represent long strings of unencoded text,
without having to separate 'encoded-word's where spaces occur in the
So the RFC is correct as it stands. The text in section 2 is specifically talking about multiple encoded-words on multiple lines. Section 6.2 covers the other case.