Mail messages are delivered with delay. In
Plesk > Tools & Settings > Mail server Settings > Mail Queue
there are no items shown.
How to check on which host the message was delayed?
It can be done with the help of Microsoft Message Analyzer .
Message Analyzertab, paste full header of message which was delivered with delay and click Analyze Headers button.
After headers will be analyzed in
Received Headerssection you will see the message delay on each of hops.