Redmine

Redmine 1.1.2 stable (Bitnami)

I'm trying to make it so an email from an unknown user to the proper issue id gets appended to the issue. However, we don't want a user email be able to create an issue (we don't want to open our system to spam).

The scenario is that we send emails to customers with the proper subject line format, and would like them to be able to respond to the redmine address and have that message appended to the ticket. The redmine address is cc'ed on the message and we instruct the customer to reply all, so that's how it gets back to the right place.

Is there a way to do this without writing code?

We don't want to add the customer as a user, we want them to stay out of the system. We just want their response on record in the ticket.