Is there a possibility to check real e-mail addresses?

You can install Mollom or CAPTCHA modules to prevent random garbage input.

why does it to you not seem to be a post from a spambot? Because it does look like a spambot post. You can also try to implement email_verify. But a captcha would be best practice.

I'm pretty sure that is not from human input and would be stopped by the CAPTCHA module.

I see that same nonsense generated on a few Drupal sites I manage that do not use CAPTCHA. I never see it on sites I manage with CAPTCHA.

There is also http://drupal.org/project/webform_confirm_email, but it does not yet work with Webform 3.x.

I still think Captcha is the way to go here. If you don't like captchas, take a look at Mollom, which only shows captchas if it suspects that the post is spam. If it looks like a legit post, users aren't bothered to fill out the captcha at all.

email_verify is still not a perfect solution. A spam bot or malicious human poster can still use a real email address (likely someone else's) in forms.

I like the optional challenges in the CAPTCHA Pack ( http://drupal.org/project/captcha_pack ). Beyond checking for human input, they can determine (through math or spelling challenges) if the poster is just plain dumb. :)

Anyway I think we've covered the set of options available to prevent these posts.

There should be a way to prevent urls in webforms. There's really no spam prevention in webform, makes me not want to use it because of that.