Have you run across a means or a file to edit in Outlook 2016+ to filter or limit time zone selection in meeting in outlook?
We want to limit selections to the timezones in the image.
The only other alternative would be to create a custom form that uses a filtered version of the timezone list to replace the 'timezone' selector.
The Outlook extensibility model (nor the Outlook object model) doesn't provide anything for filtering that list.
You may consider replacing the whole inspector layout with your form region in case of creating VSTO add-ins. See Create Outlook form regions for more information. But in that case you will have to create or replicate all the UI for inspector windows.