@prashanthal
1) Move/Copy the com.day.cq.workflow.impl.email.EMailNotificationService.xml file to "config.author" and "config.publish" folders under ui.config's module "osgiconfig" folder.
2) Make sure you have "/apps/<yourproject>/osgiconfig" path in the filter.xml of ui.config module.
3) Build and deploy your project.
4) Check if your updated configuration is showing up on author/publish server.
If the configuration is showing up by following the above steps, then it may be the configuration file is not under the correct runmode folder vs the author/publish server is running on.
Cross-check the runmode folder naming convention vs the author/publish server runmode by visiting http://server::4502/system/console/status-slingsettings
Hope this helps.