The project parameter on the Create Or Comment Handler, and other related mail handlers, is only relevant to creating new issues.

If an email comes in with an issue key in the subject, we will add it as a comment to that issue, regardless of what project it is in. We do not just do it for the project specified in the project parameter.

We should update the doco (for all relevant handlers) to say that project is only relevant when there is no issue key in the subject, and as such we are creating a new issue.