"If default email app works, Horizon Mail should work for you too.
Could you provide the error message you get?"
This is not true, I have setup multiple phones to our zimbra 8.0.4 server and they work fine. I am unable to get the horizon mail to connect. I keep receiving the error message: Unable to open connection to server: Server internal error.
Not a very helpful error message. What ports need to be open? Is activesync necessary?
Let me know, thanks