Can I filter all the issues that were created via a mail handler?

[BD]

I'm hoping to create a report that will return all of the Issues that were created via a mail handler that we have set up.

I thought about trying to use "reporter=" in the JQL, but that only works in the cases for when the user isn't already in our system (we've set createuser=false).

I'm running 5.2.5.

[codelab expert]

Every time you create a ticket via a mail handler you must set a label (this is an existing field in JIRA on an issue). This label contain for example the value "created_by_mail". Now you can filter for this issues.

[BD]

Not a bad idea for the future, but does that mean there's nothing else to key on for the issues that have already been submitted/created?

[BD]

Also, how does one "set a label" in the handler? I do not see any options in the Administrator UI or in the documentation.