Hello Jagjivan,
according to the screenshot the autoreaction method was executed (the time stamp is new and the status is " ready"). Either sender or recipient is not correct, or there is something wrong with the configuration of SCOT transaction. Please check in the transaction SOST in the client, where the job SAP_CCMS_CENSYS_DISPATCHER is running, if the e-mail has arrived in SOST. If the e-mail is not in SOST, then the configuration of sender is still not correct. Please ensure, that the sender exists in the correct client in the transaction SU01, this should be a dialog user and a correct e-mail address should be configured, and "Comm.Meth" should be set to "e-mail" in SU01. If the e-mail arrives SOST, but you do not get it, then please check configuration of the recipient, if it exists in the correct client and if it has a correct e-mail address configured. If the sender and recipient are OK, then you should check configuration of SCOT (configured in the correct client?) and if the sender job is running without problems.
You are getting the popup because it is a central autoreaction method, which is executed by an agent, this popup is not a problem.
Regards,
Alwina