I'm trying to understand your email client setup. Are you saying that you are sending out emails directly from your PC and ISP (Comcast), while using a "From" and/or "Reply To" address at your site at Lunarpages? Perhaps your emails are being bounced because some system thinks you're forging the LP site address. Maybe an SPF record added to your LP email accounts will fix it (indicate that it is OK for you to send out emails with this address). Try searching for SPF record to get the details.

Ah, that's a horse of a different color. I would still add an SPF record, so at least you won't be blamed for the spam (I think). I'm afraid that your email address (and thus your server) are still likely to be blacklisted. Be sure to copy wrongful bounces of legitimate emails (including full headers) to abuse@lunarpages.com so LP can get your server unblacklisted ASAP. If any of your site pages display your email address "in the clear" or in a "mailto" visible in the HTML source, you WILL fall victim to spammers. At the least, research how to obfuscate your email address using JavaScript so that it becomes harder to harvest. You should probably change your current email addresses if they've already been harvested. Some spammers are just going to use a legitimate domain name and make up email addresses -- did that happen to you, or did they use actual addresses?

These pages might be handy: here, and also here and here and here and here. The general idea is that you create SPF record(s) for your domain(s) and have Lunarpages support install them.

Did you use one of the SPF "wizards" to create it? If so, it should be good. Open a support ticket with Lunarpages and ask them to install it (email to support@lunarpages.com or use the web interface). Remember to tell them your record EXACTLY as the wizard created it.

Hi, I just wanted to report that the addition of the SPF record worked like a charm!  The nightmare is over!  Lunarpages support is the greatest!