Here is message from the log file C:\Program Files\Common Files\microsoft shared\Web Server Extensions\12\LOGS High #160005: Bad response from SMTP host'mail.mydomain.com': 554 5.7.1 : Client host rejected: Access denied. I resolved this SMTP issues after adding all WFE server IP into SMTP relay address. One of our DMZ WFE IP was not added into SMTP relay address. That's the reason all the OOTB overdue mail notification failed and got the below message: The e-mail message cannot be sent. Make sure the outgoing e-mail settings for the server are configured correctly.
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