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 on Hub Transport servers and Edge Transport servers. By default, protocol logging is disabled.
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.
Solution
To implement the recommended state, execute the following PowerShell cmdlet:
Set-SendConnector 'IDENTITY' -ProtocolLoggingLevel Verbose