There is a known issue with Drupal webform module - when you create a select field and want to send content of the form to different email addresses depending on selected option, you have to insert that email as a value for option in select tag. That means that your recipient's email will be visible for the robots collecting emails from the web. Well, I made a little module that allowes you to insert something like "yourname_at_" instead for "yourname@yourdomain.com" and this module will automatically replace all "_at_" with "@yourdomain.com". You can also leave the default value "@" for the domain and then you can insert "yourname_at_yourdomain.com" instead your recipient's email, the module will convert it to normal email address.

File: 

webform_email_converter.tar.gz