Aaaa. Exchange. In another universe no one would be using it. We did a project for a large university and even MS could not make Exchange run stable (for a few 100k people); they had all servers reboot at 3 am or they would crash, lose data etc. It is old school horrible as MS used to create; they improved much over the decades but I guess they did not merge that mindset in the Exchange (or SharePoint) teams.