554 Your access to this mail system has been rejected due to the sending MTA's poor reputation. If you believe that this failure is in error, please contact the intended recipient via alternate means.
Now the email host, Crazy Domains, suggests changing email settings for SMTP to the ISP server, xtra. However xtra requires each email address to be verified which isn't going to be easy with 40+ email addresses. It seems I can't just authorise one 'master' address and use that to authorise each email account to access the SMTP server which was my first work around.
So what can I do?
1. Change email host
2. Change ISP
3. Go back to using snail mail!
Thanks for any suggestions,