[Mailman-Users] Subject Lines Wrapped After Commas, (Like This?)

Stephen J. Turnbull stephen at xemacs.org
Tue May 22 05:04:48 CEST 2007

Mark Sapiro writes:

 > case, it is done by the underlying Python email library, and all three
 > of the above folded subjects should unfold to essentially the same
 > thing (i.e., the MUA should remove the inserted <cr><lf><tab>)

AFAIK the standard implies but does not say that a single CRLF is to
be inserted before "folding white space", and that the proper way to
unfold is to simply remove the CRLF.  It's not obvious to me that
using a TAB here is a good idea; I would prefer a single space.

Again AFAIK, only in the case of abutting MIME encoded words does the
standard explicitly say what to do with whitespace other than the
CRLF.  In that case, all intervening whitespace is to be removed (ie,
any whitespace that should remain must be encoded in the encoded
words).  That's obviously not appropriate for receiving MUAs for
non-RFC 2047 cases.

Unfortunately, there is no agreement whatsoever among MUAs on how to
deal with the ambiguity in "the standard as MUA-writers understand it".

The bottom line is that I have a lot of sympathy with the OP; Eudora
is not at all out of line with the degree of variation in the sample
of MUAs I'm familiar with (many do not remove the CRLF, I suppose on
the grounds that the sending MUA or user often intends a "sequence of
lines" semantics).  However, I don't see what Mailman can do except to
pick a particular interpretation of the treatment of folding, and
stick to it.  The one used by Python's email library is certainly

 > This is because the RFC recommends "folding SHOULD be limited to
 > placing the CRLF at higher-level syntactic breaks" and the folding
 > process is preferring to fold following a comma or semicolon if
 > possible.

There's no support in the RFC for this.  The "syntactic breaks"
referred to are the RFC syntax, and the Subject field has none, not
even comments.  See RFC 2822 sections 2.2.1 and 3.6.5.

I would argue that Mailman's algorithm is bogus, as it violates POLA.
At the very least the subject header should be presumed to be prose to
be broken into approximately equal lines.

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