Umango may suddenly experience authorization errors when trying to send or receive Office365 emails using the tenant admin consent authorization option.
Version 23.8.0.2 included an important update for 0365 tenant admin consent authentication. Azure app client ID's expire every 2 years and require Umango to include the new client ID in a maintenance release. This means old versions (referencing the old client ID) will stop working and new versions (referencing the new ID) require users to re-authorize Umango.
To resolve the issue, update to the latest version of Umango (23.8.0.2 or newer) then follow the authorization flow again. Once authorized Umango should be able to process emails admin consent without issue.
Link to this article http://umango.com/KB?article=132