Symptoms
When you add a new Accepted Domain (internal relay) as an asterisk character (*), the Exchange Control Panel (ECP) generates a warning message but does not hard block the new entry. However, after you add this entry, all Transport services (MSExchangeTransport, MSExchangeDelivery, and MSExchangeSubmission) start to fail.
This issue occurs in the following scenarios:
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A user adds an Accepted Domain (internal relay) as "*" (without quotation marks) in Exchange Server 2019 cumulative update 11 (CU11) or a later version.
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A user adds an Accepted Domain (internal relay) as "*" (without quotation marks) in a cumulative update that is earlier than Exchange Server 2019 CU11, and then upgrades to CU11.
Resolution
To fix this issue, install Cumulative Update 12 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
