Would be blocked by port blocking rule (rule is in warn-only mode) (Anti-virus Standard Protection:Prevent mass mailing worms from sending mail).
Seems tobe something related to McAfee
McLogEvent - Event 258
This warning is informational only and can be safely ignored.
To disable these type of messages, do the following.
Run the McAfee Virus Scan Console
Select Tools -- Alerts
Click the 'Additional Alerting Options' Tab
Change the severity folder to severity < 4