I would like to draw your attention to the following draft:
<http://www.ietf.org/internet-drafts/draft-ietf-sieve-rfc3598bis-00.txt
NB If you do review this document, but have no issues or comments,
please send both co-chairs (or the list) an email to indicate you have
looked at it. This will allow the chairs to gauge the scope of reviews
of this document to aid in our determination on whether to send it to
the IESG. Thanks.
There was a longer discussion about the draft specifying how subaddresses
are encoded, and AFAIK, the result was that the encoding should be left
to the mail system and using the subaddress extension on anything but
envelope from may give bogus results, because applying local encoding
rules for foreign addresses may be wrong.
I miss that change in the draft. Our system uses "--" as separator,
other systems use prefixes, not suffixes. Exim offers subaddressing with
any encoding that can be expressed by its string expansion operators for
some years now, so there is at least one major MTA where the discussed
model does not fit.
Changes from draft-ietf-sieve-3028bis-01.txt
5. Refer to the zero-length string ("") as "empty" instead of
"null"
So draft-ietf-sieve-rfc3598bis-00 should use "empty" as well.
Sorry for responding so late,
Michael