When you find that in the Jaspersoft report server installation process you did not enter the information to configure the email server in Jaspersoft and If the default configuration is kept the report schedules fails:
If the need is to change this email service configuration, below resolution is a quick view of how to do this.
Release: All Supported Releases
Component: Jaspersoft for Clarity PPM
if the SMTP server connection is via secure connection "SMTPS" then you may also need to enable SMTPS in jasperserver-pro\WEB-INF\applicationContext-report-scheduling.xml file:
AND change the following (to true):