Symptoms
Assume that you are using ADFS to implement multifactor authentication (MFA) in Outlook on the web (OWA). After you create download domains based on information in CVE-2021-1730, users can no longer see inline images in email messages.
Resolution
To fix this issue, install the following updates, as appropriate:
Cumulative Update 12 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019
Cumulative Update 23 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016
