As per the documentation here:

http://confluence.atlassian.com/display/CRUCIBLE/Customising+Email+Notifications

You should be able to modify the crucible-notification-subject.ftl file to change the subject of the Crucible notifications. However this seems to be broken. I tried:

1. Shut down Crucible.
2. Modify the file contents to:

Subject: TESTING ${notification.emailSubject}

3. Start Crucible.

When the email is received I would expect TESTING to be in the subject, however it isn't.