Over last weekend I had a conversation with my neighbour, with the AOL account, (Next door is a holiday cottage for them and they only come up from London a few times a year.)
As I suspected, he confessed that he only rarely looks in his spam folder and in spite of my prompting still hasn't done it. I strongly suspect that he only needs to white list the Nabble address and his problems would be over but, when you're ready, I'd welcome confirmation that Nabble is not being blocked at AOL - just in case I'm wrong.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.