Create users that do not exist from the CC list of e-mails

Currently JIRA can create a new user based on the From: field of an email, but not the CC: field.

This is related to JRA-9983 which extends the ability to add CC: recipients on an email as watchers on an issue. This has been implemented and is scheduled for a JIRA 4.0 release, however if any of the CC: recipients are not currently users of JIRA then that recipient is silently discarded from the watcher list.

It would be useful in some circumstances that when an issue is being commented on via email, an existing user could then add a CC recipient to the email and then the JIRA handler, provided configured, could then create and then add this user via JRA-9983, so that this new user would be able to comment and follow the progress of that issue.

However this introduces a problem of what permissions to give the new user..