Description: while this particular URL did not trigger our phishing detection system, this domain is well known to host both legitimate and malicious content.  The most prevalent examples of this are:

• Microsoft Azure Storage and Static Sites using the domain core.windows.net (KB)
  
• Google Drive static content shared using the domain storage.googleapis.com (Article)
  

Solution: follow-up with the sender through a different channel (eg: phone call) to ensure they uploaded the files at this location and the contents are legitimate.

Known safe URLs/domains may be added to the company whitelist via the PhishProtection portal to override the block.