OMG WOW! I`ve always wanted a midshipman mimeograph cheese abysmal exegesis shoreline belly provocation abbey coextensive convene curtsey cheese handel anomaly dyspeptic.
What`s wrong with you man?!
Venusxxx
If the email doesn't bounce they know they have a "live" email address which they can then sell on to the Spam Merchants. The fact that you viewed it means you will now probably get tons of spam - hard luck.
You may also find that somewhere in the email is a one liner for porn or pharmaceuticals.
The random garbage put in spams is designed to defeat the filters most e-mail providers use to filter out spam before it reaches your inbox.
The spammer probably intended for this random text to be invisible (such as white text on a white background) but is probably too incompetant to get their HTML coding right.
Another possibility is that you were sent a virus, but the actual virus-infected part of the email was stripped out by your ISP, leaving you with just whatever gibberish was left in the text-part of the email.