Exchange transport-rules

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Exchange 2007 supports a limited set of Regular Expressions in its transport-rules. The Microsoft technet page describing them is here. Unfortunately, I believe I've stumbled into a bug. We've recently migrated our AntiSpam to ForeFront. And part what ForeFront does is header markup. There is a Spamminess number in the header:
X-SpamScore: 66
That ranges from deeply negative to over a hundred. With this we can structure transport-rules to handle spammy email. In theory, the following trio of regexes should catch anything with a score of 15 or higher:
Those of you that speak Unix regex are quirking an eyebrow at that, I know. Like I said, Microsoft didn't do the full Unix regex treatment. The "\d" flag, "matches any single numeric digit." The parenthetical portion, "Parentheses act as grouping delimiters," and, "The pipe ( | ) character performs an OR function."

Unfortunately, for reasons that do not match the documentation the above trio of regexes is returning true on this:
X-SpamScore: 5
It's the second recipe that's doing it, and it looks to be the combination of paren and \d that's the problem. For instance, the following rule:
returns true for any single numeric value, but returns false for "56". Where this rule:
only returns true for 56 and 57. To me this says there is some kind of interaction going on between the \d and the () constructors that's causing it to change behavior. I'll be calling Microsoft to see if this is working as designed and just not documented correctly, or a true bug.

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Could the second rule be:^(2|3|4|5|6|7|8|9)(\d)$Seems like one needs to smack themselves with a gold-lined brick before their interpretation of regexes makes sense...