Maybe I'll try that next time I get a snag. But in the meantime I seem to have solved the problem. For the benefit of eveyone, including the support staff, here is the history and solution to the snags. Maybe this should be incorporated into the FAQs.
1. My websites were brand new, and in testing phase. I was using the Persits ASPMail component in an asp.net environment. I used mail.host="mail.mydomain.com" which worked fine until it was suddenly blocked by SpamCop. Why this should happen I don't know since the only person ever to get emails from the websites was me! Searching the forums revealed SpamCop had been a problem for others in the past.
2. No help from support, so I chanced upon using mail.host="127.0.0.1" and problem solved, until yesterday when suddenly all emails suddenly stopped, but no errors reported in code.
3. I looked at the headers from the JoDo forums automatic email and then used mail.host="mail2.m****here.biz" and now emails work again.
So, there it is - until the next time the email gives up. When that happens, I'll try this Live Chat feature.
On a more general point, whilst I appreciate that JoDo may be using the latest gee-whizz technology, it counts for nothing if it causes problems like this. What people want is reliability, and support staff who can actually provide support, rather than moan that prospective customers may be put off from signing up with JoDo. I would still recommend JoDo to anyone, but with the caveat that they must be prepared for unexpected problems and that they should have a good technical background so that they can figure out problems themselves.