SmartPOP2Exchange only deletes emails from the POP3 server if it has been successfully sent to the destination SMTP server.
If the SMTP server refuses the email more than 3 times it will be saved to the folder "<backup path>\DeliveryFailure" and a summary email will be generated and tried to be delivered instead.
This "error message" is caused by greylisting solutions.
For example, if you are using ESET for Server, even if you disable anti-spam capabilities in its configuration, it will not be greylisted.
To disable greylisting, the Exchange Server Transport Agent must be disabled by ESET: (in the Exchange Server PowerShell)
Disable-TransportAgent -Indentity "ESET FilterAgent
This is a limitation of the receive connector of the MS Exchange Server. It only allows a certain number of simultaneous connections from a single IP. The default value is 20.
You can query the value for your receive connectors on the Exchange Powershell:
Get-ReceiveConnector -Identity <connectorname> | fl MaxInboundConnectionPerSource
To change the value you can use the following command:
Set-receiveconnector - identity "CONNECTOR_NAME" -MaxInboundconnectionPersource 100
Please restart the Microsoft Exchnage Transport service after changing the values.
It seems you are missing the correct OLE DB Provider.
To correct this you have to go to this website from Microsoft and download the Access Database Engine 2010 in 32-bit.
Make sure you download and install the 32-bit version since the database connection is not supported with the 64-bit version.
The requested name is valid, but does not have an Internet IP address at the name server. This is not a temporary error. This means another type of request to the name server will result in an answer.