Setting up IMAP proxy balancer and SSL offloading

Hi forum,

I need to setting up a Nginx server according to this two statements:

- IMAP proxy balancer.
- SSL offloading.

I have no problems with ssl offloading and proxy but it does not work when I add upstream section in order to get balanced traffic.

Is this possible? Or is not possible setting up with this two conditions?

Best regards.
Francisco