Original post has been updated. I added a Tips & Tricks section. Basically, there were some issues with SORBS. My 71 yr old grandmother abruptly stopped being able to email me today. Apparently, her DSL reset and obtained a new dynamic IP which is blocked. So, I did some modifications to the SORBS zone that I used.
Anyway, this is a very random and I'm guessing an improbable issue for most people. But, I thought I'd post a heads up in case people complain of returned email and the reason mentioning SORBS.
ISPC3 on Debian! It's great!