EMAIL ISSUES after host installed Spam Control - Please help

I have had my cart running fine for months, then my hosting company installed a SPAM CONTROL. Now, I AM receiving my MIDDLE CREDIT CARD number email which goes to a different email account than my regular email,

BUT, I am NOT receiving emails on the ORDERS, WELCOME NOTES, Nothing from CONTACT US generated on website, and I can't SEND EMAIL from the admin area to anyone. My CUSTOMERS are NOT receiving their emails either. These emails show up in EMAIL ARCHIVE under TOOLS, but I want to receive them as I did before so I know when I have new orders and to answer customer questions.

What can I tell my host on resolving this? They are listed as ZENCART CERTIFIED, yet they have not been able to resolve this. Does anyone have any tips. I know it has to do with this new SPAM CONTROL they installed as it started happening after this update. I was receiving tons of return mail emails so I reported this to them, and they stopped the RETURN MAIL emails, but now I am not receiving anything at all.

My host says they see the emails on the server, but they are not releasing to me if that makes sense. Please help! I need my cart to function and these emails are very important. Why do I get the CC emails, but nothing else?

Thank you for your help!

There are many ideas on this FAQ:
http://www.zen-cart.com/wiki/index.php/Troubleshoot_-_Email_Problems

How about this one:> try setting the option for Emails must send from known domain? to true. This causes the email "sender" address to be more aligned to your own website, and thus less likely to be rejected while processing.

Thank you for your help! Changing to SMTPAUTH is the only setting that now works. I was using PHP before, but now it will not work. At least I found one that works now.

THANKS SO MUCH!!!!