If a file has a video extension like .mp4 but displays a generic application icon instead of a video thumbnail, do not open it.

Stacking extensions is a classic hallmark of someone trying to bypass automated email filters or security scanners that look for specific file types. 🛑 Best Practices to Stay Safe

Believing it is a movie, the user double-clicks the file. Instead of playing a video, the computer executes the .exe program, potentially installing ransomware, spyware, or trojans. 🔍 Red Flags in the File "JULIE.mp4.mkv.mp4"

The actual file extension is always the very last one listed. In the case of JULIE.mp4.mkv.mp4 , the file is technically attempting to execute as an MP4, but file names stacked with multiple video containers are a massive red flag for digital manipulation or corrupted data containers. ⚠️ How the "Double Extension" Trick Works