An email with an offer to buy textlinks

Today, I found something in my inbox, sent to me by XXXX@gmail.com, which I shall quote here with the name removed.

Hi,

Thank you for reading this. I am XXXXX XXXX and I own a number of
websites. I came across your site http://www.onyxbits.de/ today. I found it
really enthralling.
I hope you will consider my proposition of buying text-links on your site.
Let me know if you would like to know more about this.
Best regards,

XXXX XXXXX

I must confess, I am flattered by my work being called "enthralling". However, I am also skeptical of people adulating me. If in doubt, skepticism wins.
So, while I am not opposed to sponsoring in general, let's have a closer look at the message and then decide how to answer it.

The sending party uses a gmail address as the only means of contact. This is an odd thing to begin with. You'd think, that a serious business partner would properly introduce himself and his business upon first contact. Not doing so is often a sign of either inexperience or a shady nature of the proposed deal.
So let's find out, which one it is by asking Google for the name and the address. Turns out, that said person also sent similar sounding message to other webmasters, who's sites topics are not nearly in the same neighborhood as mine.
It's rather obvious by now, that the whole deal like pretty is much about buying organic looking, dofollow backlinks for the sole purpose of boostering page rank. So it's quick money with an aftertaste. Is such a deal illegal? Nope! Is it immoral? Can easy money ever be 100% morally correct? Can it come back to bite you? Of course!

So, what would I put in an answer mail in case I'd actually write one?

Dear xxxxxx@gmail.com,
I am flattered by you calling my work "enthralling". However I do not feel confident in doing business with you as you did not care to provide any information about yourself, but made it otherwise obvious, that your sole intent is to spam SERPs.
Furthermore, the only contact address, you left is xxxxxx@gmail.com. With Google reserving the right to process any email going through their system for virtually any purpose, I do not even feel confident in sending you an answer about a kind of business, Google is known to frown upon.
Even if you had contacted me about this deal using a safer means of transport, I'd still have to politely decline your request, as I am fairly convinced that you'd buy links for the sake of having backlinks alone and do not care for relevancy. In the long run, there is a good chance of Google catching you doing blackhat SEO and marking your site(s) as "bad neighborhood". Linking to you therefore puts me at a risk, I am not willing to take.

Disclaimer: I did not, nor do I intent to in the future answer XXXXXXX's email. The reasoning above is an educated guess about his motives at best. However, the chance of ending up in a bad neighborhood is not appealing at all and definitely not worth the risk for me.