ReportingServicesService!emailextension!4!04/19/2007-17:05:59:: Error sending email. System.Runtime.InteropServices.COMException (0x80040211): The mes

ReportingServicesService!dbpolling!21!04/19/2007-17:05:59:: NotificationPolling finished processing item 0ed42bc8-26ab-4454-819c-db894e68c973
ReportingServicesService!library!4!04/19/2007-17:05:59:: i INFO: Initializing EnableExecutionLogging to 'True' as specified in Server system properties.
ReportingServicesService!emailextension!4!04/19/2007-17:05:59:: Error sending email. System.Runtime.InteropServices.COMException (0x80040211): The message could not be sent to the SMTP server. The transport error code was 0x800ccc15. The server response was not available


A firewall was blocking traffic from the Report Server to the Exchange server. It blocks emails being sent from the server on port 25.
Add an exception for the ReportingServerService.exe Anti virus program
and now emails for data driven subscriptions of reports should fire

OR

CAUSE:
The configuration for the Email service was incorrect.

RESOLUTION:
change the SendEmail setting to 2 and removed the value for
SMTPServerPickupDirectory in the RSReportServer.config file.