Hi Hmaltz,
Before moving on, I would like to confirm the following information:
1. Does this issue happen in both Outlook Web App (OWA) and Outlook?
2. What’s the type of the problematic emails?
If the issue occurs to the HTML e-mails, you can refer to the following:
To show the images in the HTML message, you can perform the steps below in Outlook.
1. Launch Outlook, and then click File -> Options.
2. In the Outlook Options window, click Trust Center. Then click the "Trust Center Settings..." button under Microsoft Outlook Trust Center.
3. In Trust Center, click Automatic Download. Then clear “Don't download pictures automatically in HTML e-mail messages or RSS items check box”.
4. Click Ok. And then click Ok.
To show images in OWA, please clear “Don’t trust email unless it comes from someone in my Safe Senders and Recipients list or local senders” under Blocked Senders on Block or Allow Panel.
In addition, if the Internet Explorer (IE) has been set with enhanced security feature or with high security settings, the picture in HTML e-mail will be prevented in the OWA. We will get an alert to confirm the open. If you choose Yes, it will open well. Otherwise, it will not show the picture.
Thanks,
Cherry Wang