Issues are not transitioning when commenting via email

Steps to reproduce:

1. Create a support request from the Customer Portal
   
2. By default, the status of the ticket will be "Waiting for Support".
   
   
3. A support agent responds to the support request which changes the status of the ticket to "Waiting for Customer".
   
   
4. When the customer replies back via portal, the status of the ticket is changing to "Waiting for Support", but when the customer replied via email, the comment has been added, but the status is not changed. It is still "Waiting for Customer".

• Comment via Portal
  
  
  
• Comment via Mail
  
  
  

Expected behaviour:
The status must be changed to "Waiting for Support" when the customer commented via email.

Issue is reproducible using JIRA 6.2.7 and JIRA Service Desk 1.2.6.1