I tried using auto-replace watched word to eliminate junk that Outlook adds to the bottom of an emailed post, such as this: ![image001.jpg|45x45](upload://yS0BlfXTqaPhoqyF6LaZLwt7xJv.jpg) but it still got through.
![image001.jpg|45x45]* is properly recognized by the test:
The watched words are replaced during the process which converts posts from Markdown to HTML and it applies only to text fragments. Unfortunately, it means that it does not apply on other Markdown markups.