I cannot add an email to a new Service-desk project

[Kim Wickell]

The message i receive is 

Error

The email address you entered is currently used by another project's email channel. Please choose another email address.

The email is used as notification email but that is it.
Where should i look to find which projects use incoming emails?
I have looked in every place i could think of but no sign of this email being used anywhere. 

I have had Service Desk installed on the server before i updated to JIRA 7.

[Paulo Hennig]

In your other Service Desk projects, don't you set this email?

Case not, could you kindly filter in your log files in order to have a better troubleshooting of the problem as the following example

grep "emailaddress" <JIRA-HOME>/log/*