Email This Issue logs a lot of information to the Jira log files. However, to make this information visible a few steps are needed:
Under Jira Administration / System / Logging and Profiling, configure a new logging level with
This needs to be every time after Jira starts up. The new logger will enable the output from Email This Issue to appear in the log files.
The most common way to monitor the log is to access them in the files system under the Jira Home directory and do some log file tailing like "tail -f atlassian-jira.log"
However, there is a more convenient method as well. Last Log for Jira is a free addon at the Atlassian Marketplace. It is a brilliantly simple but tremendously useful tool and reveals logfiles to Jira administrators without having to access the server itself Jira is running on.