KB1265: Troubleshooting Exchange AIR - Veeam Software
https://www.veeam.com/kb126506.10.2011 · Solution. Check application group, make sure that DC is first in the list, otherwise Exchange won't be operational, and make sure that you specified the DC role for the Domain controller. The other roles are less necessary for restore purposes. Also make sure that in application group, you also have Mailbox Store server and CAS server.
KB2969: Veeam Backup for Office 365 Complete Permissions
https://www.veeam.com/kb296926.06.2019 · Veeam service account permissions. 1.a. Exchange Role. Configuring permissions for Exchange Online. Create a role group in the Exchange Admin Center as explained here. Add Roles specified in the User Guide. Add the Veeam Service account to role group members and save the role group. Connect to Exchange Online PowerShell module and run the " Get ...