As I said before, there is no consensus to go from SHOULD to MUST in the
last sentence. Also,
"vacation" doesn't cause mail delivery, so here is a replacement text:
Implementations MUST prohibit the execution of more than one reject
in a SIEVE script. "Reject" MUST be incompatible with the "vacation"
[VACATION] action. Implementations SHOULD prohibit the use of "reject"
with actions that cause mail delivery, such as "keep", "fileinto",
"redirect".
I'm happy with that.
I've just noticed that in your original proposal you dropped "discard".
"SHOULD reject be incompatible with discard"?
Discard just cancels the implicit keep, as does any other action, so
discard+?=?. I don't see why discard+reject can't = reject. I think the
sentence is superflous, so agree it should be dropped.
Nigel