Symptoms
In Microsoft Exchange Server 2019 and 2016, you create a shared mailbox, and grant full access and "send as" permissions to a user. The user configures the shared mailbox to copy messages to the Sent Items folder, and then sends a message that includes BCC recipients from the shared mailbox.
In this situation, the message appears in the Sent Items folder of both the user's mailbox and the shared mailbox. However, the BCC recipients appear only in the message copy in the user's mailbox, not in the shared mailbox.
Resolution
To fix this issue, install one of the following updates:
Cumulative Update 11 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019
Cumulative Update 22 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016
References
Learn about the terminology that Microsoft uses to describe software updates.
