What are the garbled emails I receive?

[rsdesigner]

I have a quick enquiry form on my website, I often receive garbled emails. I assume these are being sent by machines not people but why, what do they achieve? Are they harmful?
The message I get will be something like:

From: hsyhlktlho
Tel: hcgpdvot
Email: nwmseduknc@pfflyg.com
Brief: pqoolste.hsbqijdeftjho, http://www.ywcpaxlupc.com wdddtbzzaj

I would prefer not to add captcha to the form unless these emails are harmful.
Any advice/explanations most appreciated.

[seandisanti]

usually they send you to a site with some flavor of malware embedded that attacks when you access the site. Some people will just click on the links if they don't understand the message because they're trying to figure out what the sender intended. Also sometimes the emails themselves are composed in html and can do some pretty nasty things themselves. The old rule of thumb should still apply, if you don't know the sender, don't open the email. Beyond that, if someone you DO know sends you a link out of the blue with little or no explanation, don't click it until you've contacted them via another medium to make sure they really sent it to you.