Hi @Murat Gökhan Engin ,
I'm wondering why the Outlook Windows App and the web browser display the email body in the email list.
This is because of the default message preview settings in Outlook client or OWA. If you don't want to display the email body in the email list, you can change the setting using steps below:
- Outlook windows app
Click View > Message Preview > Off
- Outlook web app
In the navigation bar at the top, select Mail, and then select Settings
Layout, Hide Preview text:
However, from the screenshots you shared, guess you are also concerned about the image URL showed in the preview in Outlook windows application, right?
Based on my experience, this could be the expected behavior in Outlook client and it's probably because Outlook desktop client renders an email differently than OWA.
If what you are after is to prevent recipients from seeing the image URL, I'd recommend trying to adjust the email content you generated using the custom application. For example, you can try adding an extra blank line above the image.
Actually, I also would like to know if a specific tag for this purpose should be set when we send emails from our custom applications.
Personally, I am not familiar with this situation, but I came across the link below which discussed a similar situation. You can take a look at the suggestion there and see if it can be adapted to your issue as well:
Short preview of emails in Outlook shows the image src and not the alt text
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.