You mail provider has decided you are sending spam is what is going on. Have you contacted them?

I haven't contacted them but I will right now.

Is it possible it's because of one of the people on the list I'm trying to send it too? I ask this because I sent a test email to myself and I didn't get the error message.

I'll let you know what I hear from my email provider.

I provided the information to my email provider that they requested and the problem seems to have been fixed.

I asked for an explanation of what the problem was but still haven't received a reply yet.

Thanks for your earlier response...