Actual behavior:

JIRA is adding the Catch Email Address as a Watcher of an Issue when the E-mail Address belongs to some JIRA User and the Mail Handler has CC Watcher enabled. Leading to a possible Mail Loop.

Steps to reproduce:

1. Create a Project and associate with the Default Notification Scheme;
2. Add an Incoming Mail Server and Add a Mail Handler that has the CC Watcher enabled and set a Catch Email Address the same as one JIRA User.
3. Send an e-mail to that address.
4. JIRA will create the issue and add the Catch Email Address address as one of the watchers.

Expected behavior:

JIRA should not add the user in the watchers list.

Notes:

1. This is affecting JIRA Service Desk Email Settings as well, in this case it is the request participants.
2. Tested on JIRA Core 7.0.2 and without the "Catch Email Address". If there is a user with the same email address as in "To" of a sent email, it will added as a watcher.

Workaround:

Modify the user email address or the Catch Email Address being used.