Symptoms
A certain search condition fails to provide expected results when you use Outlook online mode in Microsoft Exchange Server 2019. For example, you create an email with subject "S150757". When you use the keyword "S150757" to search for the email item, no result is returned, but you can get the expected result when using the keyword "s150757".
Resolution
To fix this issue, install the Cumulative Update 9 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
References
Learn about the terminology that Microsoft uses to describe software updates.
