I am using SQL Server 2012 Reporting Service. I have 5 Reports those need to deliver on email with the attachment as excel. But I'm facing issue some time report delivered some time not. I check the status of email delivery in Report server manager and status showing error:
“Failure sending mail: Service not available, closing transmission channel. The server response was: Unexpected failure, please try later”
I unable to understand how to troubleshoot this error. I cross check SMTP server it fine. I'm facing this issue after upgrading from SSRS 2008 to 2012. Earlier the same SMTP used and I never face such kind of issue. Please suggest how to troubleshoot it.