Another suggestion that will help make false positives and whitelisting easier to resolve.
In the connection filtering window, click the Exceptions button, and add you postmaster address (or a less spammed address such as whitelist[at]yourdomain.com, though technically the postmaster address really shouldn't be filtered). Then configure your custom message on the blocklist screen to something like:
QUOTE
Your mail server %0, has been prevented from sending mail to yourdomain.com because it is listed on the SpamCop block list. To be whitelisted, please send an email from the same account to postmaster[at]yourdomain.com
That gives a user that is blocked all the import information they need:
Who blocked them (yourdomain.com)
Their connecting IP address (Exchange puts this in place of the %0 automatically)
Why they were blocked (on the SCBL)
And most importantly, what to do about it (contact postmaster[at]yourdomain.com)
By having the postmaster[at]yourdomain.com listed in your exceptions, their email to that address should bypass the connection filtering, allowing you to look at the headers, and whitelist their mail server if you feel it is appropriate. Yes, this means that you will have to deal with spam on the postmaster account, but most spammers seem to auto-listwash postmaster and abuse addresses as they know we will report them as a matter of course.
When this happens, I generally tell them that the whitelisting will be temporary, and that they will still need to deal with the problem of getting of the BL, that seems to encourage them to get their IT department involved and get things fixed.