The CBL is specifically intended to be used to filter email coming into a mail server from the Internet.
In "tech-jargon", it's intended to be used on email going to your MX, NOT your user's "outbound SMTP server", nor for anything other than email.
As this is not a supported use of the CBL, please do not contact us about these problems (unless this is a static IP address that belongs to you only, in which case you should treat this is a virus/proxy infection - see: scanning your machine).
Instead, you should be contacting the provider of the service you're trying to use.
The best you can do is ask the provider (ie: IRC owner) to exempt your IP, or suggest alternates. Open proxy DNSBLs are often used by IRC operators for good reason, and the CBL is pretty much equivalent to an open proxy DNSBL.
In other words, we don't support this use, but we don't think it's a bad thing to do either: we do not discourage IRC operators doing this - it's up to them.