Hi @Genesis Support ,
Everything is working well apart from when I try to click on the "Signature" and Stationary and Fonts" options in Outlook, it crashes Outlook.
I am currently running the same build of Outlook for Microsoft 365 (Version 2019, Build 16.0.14430.20292, 64-bit) but on Windows 10, so I just tried clicking on the "Signature" or Stationary and Fonts" options, it worked fine without crashing.
A quick research on what you described brought me to this previous known issue: Outlook freezes clicking the Signature button. But it's about "Outlook freezes" while your issue is "Outlook crashes", and the pre-installed Microsoft Office desktop apps involved usually only affect Windows 10 but you are running Windows server 2019, so it seems different from your scenario.
Given this situation, could you have a look at the Event Viewer on the machine when the issue occurs? If there's any relavant event recorded out there, you can share it here after removing all personal information so that we can see if more clues can be found.
Besides, on your machine with 64-bit Outlook, please open registry editor(regedit) and locate the following registry key, verify that it's pointing to the correct location for outlook.exe. By default, the outlook.exe location is "C:\Program Files\Microsoft Office\Root\Office16\OUTLOOK.EXE". If it's pointing to an incorrect path, change it to the right value after backing up the registry.
Computer\HKEY_CLASSES_ROOT\CLSID{0006F033-0000-0000-C000-000000000046}\LocalServer32
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