This issue occasionally crops up in Outlook 365, although it has become rarer with recent updates. If your Outlook client is experiencing graphical glitches such as the user interface being garbled, or emails being unreadable, the steps in this article are the most likely solution. There are a lot of different ways it can look depending on your device. A couple of examples of what this can look like are:
1. In Outlook, go to File in the top bar, and then options in the sidebar.
2. Select the “Advanced” tab in the popup.
3. Scroll down to the Display section, and tick “Disable hardware graphics acceleration”
4. Press OK, and the issue should be resolved.