I've seen similar behaviors with links in subscription emails not working properly or redirecting to incorrect pages.
A possible explanation and a workaround is documented in the article below.
Hope this help
Thank you for the reply. When I click the empty image in my email (Outlook Desktop) it does open the workbook in Tableau Server with the web image available. So the KB article you shared is for email broken links but in my case, it is working.
This is what I see in Tableau Server but I see the image empty when received in Outlook. The image below is what I also expect to see in Outlook.