Currently we can’t send email to anybody with an Apple based email account. I have looked into this in depth and it is due to overbearing and stringent policies the Apple seems to have created recently, and only users of these services can adjust things on their end (and it’s really complicated).
This problem will not be solved, I now understand.
Since the system cannot send mail to these half dozen of so users the only way they are going to find out about this is if they log in to the web interface. It’s a conundrum. For those Apple users that do manage to login, please change your mail preference setting to a non Apple service.
I’m sorry about this but that’s the end of the matter. There’s nothing wrong with Apple mail services (me.com and so on), it’s just their attitude to mail from our list being sent out via Amazon Simple Email Services.