I had sent the same messages to about thirty addresses on about 20 ISPs, spread over 8 otherwise identical messages.
In some cases it was multiple mixed addresses (& "cc:") on different ISPs on a single message.
At present, the majority of the Addressee Recipients have confirmed receipt, either by e-mail or by telephone.
Only the HOTMAIL Addresses have not received the messages.
If the Blacklists allow Complete Rejection of EVERY e-mail originating with specific ISPs, whether truly SPAM or not, then the whole global e-mail system would grind to a halt, if spamhaus included every ISP.
Your description of "spamhaus" suggests that it corresponds to the Spam Filters that Individual Users can set up on their own Mail Boxes, to discard of Spam etc as it arrives at their individual input port, rather than a generalised system, otherwise why did my other Addressees receive the Messages without problem one confirming by phone about 30 minutes after sending; and in two cases to the extent of Forwarding them on, at my request by Orange e-mail, to two of the HOTMAIL addresses without any problems?
I have literally just received confirmation that both forwarding actions to those Hotmail Addressees, were successfully completed, the Forwarders being on other non-Orange ISPs; and could only have forwarded those after receipt from my Orange Address.
The contents were not in any way contentious.
Extract from www.spamhaus.org
At 21 July 2011 the Spamhaus Blocklists are protecting 1,438,216,000 users mailboxes
Note that the claim relates to "users Mailboxes".