Hi Gary!
As Wazoo has explained, the receiving ISP is the one that chooses to make use of the SpamCop BL. Typically ISPs choose to block rather than filter causing the issue you describe.
Looking at the failure messages you provide above I'd say your South African contact is working through an ISP who has chosen to block based on the SpamCop BL. So your colleague probably has it within his power to address the problem with his/her ISP.
That said, many ISPs choose to use the SCBL because it is very responsive to spam problems and helps them reduce the load of spam flowing through their servers. This saves them money on bandwidth and Email storage.
You also have the opportunity to work towards resolving the problem from your own end. You appear to be sending your Email through an ISP that, for whatever reason (could be accidental or intentional) has a flow of spam flowing through the server. You could work with an ISP that does not have such problems and your Email would flow freely. There are many such ISPs you could switch to in order to avoid the problem but still retain your current incoming Email address.
Andrew