Terry, just wanted to let you know I edited your post to change the email addresses - I didn't want the addresses to be scraped and the users to start receiving spam.

You didn't mention this, but I'm guessing the sender is a business and using their own SMTP server for outgoing email (as in they have a website/domain/hosting package). If that is the case, and I suspect it is, the most likely reason I can think of is a misconfiguration of the DNS record for the domain. If they are on a shared hosting package it could be a simple misconfiguration of the exim configuration file. Actually, it looks like Vodahost is the hosting provider and I believe all their packages are on shared servers.

What's their domain?

http://www.spamcop.net/w3m?action=checkblock&ip=74.209.214.7 <- This could be a large portion of the problem.

I think it best to open a ticket with your host and ask them to address the SMTP Banner issue. Currently your domains IP resolves back to vodahost14.com and it should resolve back to masterpac.com. It shouldn't be too hard for them to correct. I believe it's a simple edit of the exim.conf file, but there is a caveat to this - each time they update cPanel that edit could be lost. I imagine that would take steps (create scripts) to prevent that but you should be aware if it happens again.

Next thing I would check is if the host requires SMTP authentication prior to sending. You can check that by creating a new account and configuring a client, but don't enable the SMTP Authentication in the client. If you can send without authentication you have a problem that could significantly bear on your blacklist entry above and you should contact the hosting provider to enable authenication.

After that I would do a thorough scan of any PC's that send/receive email for that domain and make sure then aren't infected and sending email without anyone's knowledge.

Here's a good tool to check mail issues - http://mxtoolbox.com/

May I suggest Hostgator?
http://secure.hostgator.com/%7Eaffiliat/cgi-bin/affiliates/clickthru.cgi?id=deputy963

carbonterry2 said

His business has a business account with Charter.net and will host for free........FWTW
Thanks for your help

My .02
Look VERY carefully into what they offer, what they allow, and what software they run before firing up with an ISP. Hosting is often an afterthought for a company who's bread and butter is providing access.