Need the option to send the invitation notification to an existing customer.

Problem Definition

Need the option to send the invitation notification to an existing customer.  

In case a customer is a part of the site and is being invited to any project within the same site the notification is not sent to the customer about the activity. 

Steps to Reproduce: 

1. Get to the customer section and add the customer.
2. The Customer section shows the blank status and no Resend invite under Actions. 
3. The customer do get added to the same project 
4. However there is no notification sent to the customer informing the same. 

Why this is important

Easily test changes on a dev environment to make sure everything functions properly before making the same changes on production instances

Expected Results: 

The notification should be sent to the customer informing them about the same action. 

Actual Results: 

No notification gets sent to the customer. It only adds the customer in the background.