If some of your recipients are reporting issues with images not loading correctly, this is related to their Outlook security settings for HTML emails.
Specifically, the red box and x on images occurs as a result of when the Internet Explorer Security setting "Do not save encrypted pages to disk" option is enabled.
Note: Even if you do not use Internet Explorer, the Outlook application is connected to this browser.
Please ask your administrators to follow the below steps to resolve the issue, or encourage employees to do it on their own basis.
1. Exit Outlook
2. Open Internet Explorer and go to Internet Options via the settings icon on the top right
3. Under "security", disable the "Do not save encrypted pages to disk" option and select OK.
4. Start Outlook
*If you are unable to disable this option, please contact your system administrator.
If this still does not start to display the image correctly, then you will need to check the following:
1. Open Outlook and click "file".
2. Options > Trust Center > Trust Center Settings > Automatic download.
3. Uncheck the "Don't download pictures automatically in standard HTML email messages or RSS items" option