Known Issues and Limitations:
For Microsoft Outlook, the preliminary releases, like Insider releases, or releases provided through
Monthly Channel Updates are not supported; Veeam supports only RTM/GA versions of this product. For
more information, see this Microsoft article.
Two question do arise:
What is Outlooks role here? It is the enduser Application. We are only backing up data
Why is monthly channel not supported?
Quoting the linked microsoft article: We recommend Monthly Enterprise Channel if you want to provide your users with new Office features each month, but only want to receive one update per month on a predictable release schedule.