Technical Tip: FortiMail will not submit the Spam URL to FortiSandbox for scanning

• If the URL has been categorized as a Spam URL by the FortiGuard AntiSpam (not FortiGuard Web filter), the FortiMail will not submit the URL to FortiSandbox for scanning because it can be detected by FortiMail. This behaviour is expected behaviour.
  
  
• The Objective is to improve the performance of the FortiSandbox.
  
  
• If the sender is being safe-listed, which will bypass the entire antispam scanning, and if the URL is categorized as a Spam URL by the FortiGuard AntiSpam, FortiMail will not submit the URL to FortiSandbox for scanning, and eventually the email will be delivered to the user.
  
  
• It is possible to check whether the URL is categorized as a Spam URL by the FortiGuard AntiSpam (not FortiGuard Web filter) using the link Antispam.

Also note that there are two checks performed for a URL, one with the 'FortiGuard AntiSpam database' and the other with the 'FortiGuard Webfilter database'. For more details, see this article: Troubleshooting Tip: URL is blocked as SPAM, although belongs to an allowed FortiGuard URL category.