My spouse and I have been separated for a year. We have no children together, no common property, nothing that should be an issue. The only problem is he lives in South Africa (he’s originally from there, lived here in North Carolina for the duration of the marriage, then moved back to South Africa as soon as we separated). Can I still use certified mail as a way to deliver the Civil Summons to him, or is there a better approach? I have been told that he doesn’t need to appear in court. Thank you so much! 
Yes, you may serve him by certified mail, return receipt and he need not appear in court.
I have the same issue, and I just looked on the USPS website and Certified Mail is only available within the US and to certain US territories.
The USPS does, however, offer Registered Mail with the option for a return receipt for certain countries. Is the main requirement that there be a return receipt showing personal delivery to the intended recipient?
Yes.