I know what mailcore2 calls I'm making, and I know the account, I don't know if the server (Apple's iCloud email servers) is sending something utterly incorrect, or if they are borderline correct and mail core isn't quite parsing it correctly. I don't know if it is related to some specific email message, or what. I don't even know if I'm somehow misusing mail core here.
In particular I'm not asking anyone to debug my (potentially) buggy code. I'm looking for the short cut to "hey I want to see what bytes the server is sending me and what bytes I'm sending the server".
If it weren't for TLS I would debug this with tcpdump.