In my email today comes this:

Dear Lynn,

My name is Tracey Rosengrave, Marketing Manager for Xlibris Corporation, a Print-On-Demand Self-Publishing company. We are sending you this email because we have either learned about your passion for writing or we have had the pleasure of coming across some of your work. If you are interested in self-publishing, I’ve included a brief description of who we are below.

Key phrase there is SELF-PUBLISHING.

Everyday we help authors by offering flexible, inexpensive methods of publishing, editing, marketing, distributing and selling books both in trade and full color. I understand that each author has different requirements. And that is why we offer packages that are tailored to your individual needs.

Next phrases to pay attention to: BY OFFERING […] INEXPENSIVE METHODS […] PACKAGES TAILORED TO YOUR INDIVIDUAL NEEDS. (Honestly, where is the editor here? I'd write it thus: I understand each author has different requirements, which is why we offer packages tailored to individual needs.)

You should, in general, not have to pay someone to publish your work. They pay you, not the other way around. There are exceptions, sure, but be sure you know the difference before embarking on self-publishing. It's not necessarily a bad thing, but it's not the best scenario either. For a good perspective on POD, visit POD-dy Mouth (and no, the Lynn Harris mentioned on her blog is not me).