What can I do to prevent them from blocking Email I want to receive? Or at least verify they are blocking it.
Its hard to verify, unless you can get the Sender to verify. One thing you should do is go to the webmail and make sure that you have its SPAM blocker set to place blocked email in a folder rather than just deleting it. Then periodically check that blocked folder. If you do find the email you want there, you can setup a rule to send you the emails anyway. Note certain emails that exceed limits are blocked before they ever reach your ID, e.g. exceeds more than a certain number of people addressed to (100?) etc. And of course it could be being blocked before it ever reached Verizon.
I went on to webmail and the spam filter was set to delete, so I changed it to the folder option. I'll see what happens when the next newsletter is sent.
By the way, the sender verified it was sent. He thinks it's being rejected because of the imbedded ads.
Anyway, thanks for the response.