Email only interface to Jira

Some customers want to hide Jira from their Customers who lodge support requests though email.
They want the Customer not to know about Jira but rather interact purely by email.

The following are some of the problems that the current system has with this:

1. When a user sends an email they will recieve an email back saying they have an account at Jira and can then log on.
2. They should most probably be put into a special group. (could be specified in the service)
3. They can log on to Jira (they should be blocked) I.e. They should have Use permisions but not Log on permissions.
4. They should receive Notifications without links back to the web pages. (Internal Users should still get the normal ones)
5. By default these users will receive Notifications made by themselves. The default should be set to False.

(That is all I can think of for now.....)