Information
A protocol log is a record of the SMTP activity between messaging servers as part of message delivery. This SMTP activity occurs on Send connectors and Receive connectors that are configured with the transport service on Mailbox servers and Edge Transport servers.
Rationale:
If events are not recorded, it may be difficult or impossible to determine the root cause of system problems or the unauthorized activities of malicious users.
Impact:
Additional storage space will be required for the log file.
Note: The default file size for the protocol log is 10MB and is stored for a maximum of 30 days. This may need to be adjusted to adhere to company retention policies.
Warning: Do not enable Protocol logging on an Edge Transport server that has been subscribed to the Exchange organization by using EdgeSync. Those changes need to be made in the Transport service on the Mailbox server. The changes are then replicated to the Edge Transport server the next time EdgeSync synchronization occurs.
Solution
To implement the recommended state, execute the following PowerShell cmdlet:
Set-ReceiveConnector 'IDENTITY' -ProtocolLoggingLevel Verbose
OR
Perform the following actions:
Launch the EAC (Exchange Administrative Center).
Go to 'Mail Flow' on the left and click on the 'Receive Connectors' tab.
Double-click on the receive connector to be modified.
Change the Protocol logging level to Verbose and click Save.
Default Value:
None