Subject: matching bounce messages

From: Tony Finch <[email-masked]>
Date: Mon, 29 Nov 2004 18:19:33 +0000

We're using the CMU Cyrus Sieve implementation. A few of our more advanced
users have asked how to identify bounce messages in a Sieve script. The
obvious doesn't work:

	if envelope :is "from" ""

The best phrasing we have seen is

	if not envelope :contains "from" "@"

which is a rather ugly circumlocution. RFC 3028 doesn't say anything about
null return paths, which is clearly an omission. As a result the Cyrus
behaviour is hard to classify as a bug.

Tony.
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f.a.n.finch  <[email-masked]>  http://dotat.at/
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