Email this issue allows you to send manual (ad-hoc) emails using the Email button in the issue screen. When you open the email screen you may want to see default recipients, apply default email format and various other mail options.
Just like any other context like entities in Email This Issue, Default Settings may also be applied to one or more projects, one or more issue type or you can even specify a JQL filter criteria to precisely target the defaults to issues.
Once configured, the email screen will be initialized with the best matching default settings. If none applies to an issue, the global defaults from the Configuration tab will apply.
In order to make sure the default settings are applied, user options should be disabled in Configuration
How Default Settings are Applied
There may be multiple default settings configured. Email This Issue finds the nearest matching default settings for an issue when the email screen opens.
The evalutation if the default settings is done the same way as the evaluation of Contexts.