I've been getting an increasing number of requests (currently at around 100K per day) with user agent Mozilla/4.0 (compatible;). Usually, when I see a user-agent or requests that look suspicious I do my research (IP lookups) and block them as needed. However, this one I can't make my mind up about. Looking at the IP's they are from companies like Bosch and Audi, in Germany. I read that some proxy servers (could be company proxies) can use this user-agent. I don't want to block people at Bosch or Audi from being able to get to my site.
Anyone's got any experience with this user agent? Can anyone confirm if this may be indeed a company proxy? Or is this plain-o' spam?