scan.messages.rules exceptions

[Stef Morrell]

I have a ruleset for what should and should not be scanned.

Scan Messages = %rules-dir%/scan.messages.rules

So far, so good.
If the ruleset simply reads:

# Default no, do not scan.
FromOrTo:       default         no

Then when I mail myself from an alternate address, it's not scanned - expected behaviour.
Again, when the file reads:

# Scan my email
To:     *@aoc-uk.com    yes

# Default no, do not scan.
FromOrTo:       default         no

Then my email is scanned, again expected behaviour.
When I try to create an exception with the following: 

# Don't scan Stef's email
To:     stef at aoc-uk.com    no

# Scan my email
To:     *@aoc-uk.com    yes

# Default no, do not scan.
FromOrTo:       default         no

Then, unexpectedly my email is still scanned.

I thought rulesets were parsed top to bottom and stopped at first match, but that's not the behaviour I'm seeing. What I need to be able to do is make exceptions (ideally using From: And To: syntax) for individual email addresses. 

I'm doubly confused as I have a server running MailScanner-4.84.5-3 which I'm sure works like that (or has been broken for months without anybody noticing), but the new one I'm setting up with 4.84.6 is behaving as above.