OT mail spam question

[Vintage Computer Festival]

I just moved my mail server to my internal office network.  The IP block
I've been assigned apparently used to be used for dynamic DSL users.  The
problem is, at some point someone used one or more of these IP addresses
to send out spam, enough so that my entire Class C block is blacklisted in
some database.

I'm getting reject messages occasionally when I try to send someone
e-mail, like so:

   ----- Transcript of session follows -----
... while talking to smtp.secureserver.net.:
>>> RCPT To:<mike at sccpc.com>
<<< 553 66.120.4.* mail rejected due to excessive spam (Spam received from
66.120.4.201)
550 5.1.1 <mike at sccpc.com>... User unknown

It's a very small percentage of my mail, but it's keeping me from
responding to people sending me inquiries in some instances.

How the *hell* do I track down what fuckwit is blacklisting my address?

I appreciate the efforts people go through to thwart spam but this blanket
blocking bullshit really pisses me off.

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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