Hi Steve,
If possible, would you please provide a screenshot to us via sending it to
GBSD TN Office Information Collection ibsofc@microsoft.com?
Based on my research, the Outlook default message class is IPM.Note, which is necessary to control the icon display. This means
the message class for the emails coming from SharePoint workflows must be IPM.Note for the icons to work.
If the message class for these SharePoint workflows emails is not IPM.Note, you described issue may happen.
We can confirm this by displaying the Message Class field for your emails in table view. To do this, please follow:
1. Click the folder where these emails are stored.
2. Click View tab > View Settings, then click Columns button.
3. In the Show Columns dialog, under "Select available columns from" heading, select "All Mail Fields".
4. Find and select Message Class field, click Add button.
5. Now, you can see Message Class field shows in the right pane. Select Message Class, drag and then drop it to the top of the right pane list.
6. Click OK. Click OK again.
7. Check if these the message class for these SharePoint workflows
emails is IPM.Note.
Please let me know the result.
Regards,
Steve Fan
TechNet Community Support