Several antivirus scanners and mail providers open links to check for malware. I believe they add some randomness to either bust through cache or to detect if t

Several antivirus scanners and mail providers open links to check for malware. I believe they add some randomness to either bust through cache or to detect if the URL is encoded as an exact match (some exploit kits will redirect to google.com if you alter the URL in any way or after x requests to the same URL).