"I take it from your comments that some email hosts are actually scanning the entire content of all outbound emails eg Orange?"
It would be better to say "Most" not "some"
But the key point is this
"According to 'support', both these ISPs have a 'hair trigger' on spam and it takes very little for them to assess a mail server as a problem."
That is not true. AOL is no more likely to block than anyone else. This is your e-mail host casting blame incorrectly.
If AOL are blocking, others will be also. You need to find just which blocklist your server is on
Something else to remember in all this is that AOL can be a bit funny about incoming e-mail from competing companies.....
for instance I've noticed many times that if I send a test e-mail to one of my AOL accounts from a Yahoo account it goes into a black hole. No bounceback message, it just vanishes. Yet the same message appears in my Gmail or Hotmail or other accounts without delay.
Last edited by Milo Minderbinder; 22nd Jun 2013 at 08:29.