Summary: 
Currently the relation is 1:1 between each project and the email configured on the channel meaning that each JSM project requires a unique email to be configured on the channel "Unless using an add-on such as JEMH".

Suggestion:
Customers would like to natively have the ability to configure the same customised email address for incoming email for multiple projects which provide more flexibility for our end-users to support their customer via a single email or distribution list.