Using gmail w/ SideKick not getting back into ZOHO CRM

Using gmail w/ SideKick not getting back into ZOHO CRM

So, it's a unique issue, but one most sales organization would needs addressed. We do a lot of outbound work and this includes using Zoho's mail editor in CRM to send follow-up messages. So, I can call, leave a message and then send an email and this outbound message logs in both my Zmail and Gmail outbound. This is good! Issue being is that when the client replies (I have tested this with a personal account), the email does not make it back into the CRM where I would be notified of an inbound message. I then have to keep checking my email client which is counter intuitive to using a centralized CRM. 

- How can I get these emails back into my CRM to track email chains / discussions? 
- How can I do this using my corporate Gmail system and not using Zmail (if at all possible)?

I have left two messages this week with no callback and it's beginning to impact my business and our relationship. How can I get the email working property without having to utilize the Zoho mail which does not allow apps like SideKick to be installed?