Hey All, 
I'm trialling Zoho CRM with a view to move from an old system we're using and getting the email functionality to work how we need it to is integral to our potential switch. Although Zoho's email functionality in the CRM is looking great, I can't currently see a way to do exactly what I need it to do so hopefully someone, or a zoho rep can help: 

So a bit of background; we are a Paralegal/Legal Services firm. 
- I'm using the default Zoho CRM 'Contacts' module for our Client contact records. 

- I've created a custom module called 'Casework' which tracks the complete progress of a clients case. 
- I've created a custom module called 'Council Representatives' which is an additional category of 'Contact' but I prefer to keep these separate from the Contact module I use for the clients. 

When we have a new Casework Record, all involved parties (Clients or Council Representatives) will be attached to that record via lookups.  Therefore we will often have Clients and Council Representatives attached to multiple Casework Records. The Casework module is where we will be actively working from the most.  

The email indexing on Zoho CRM seems to only be able to index emails based on the automatic recognition of the email address. I am able to see the emails in the Casework records also because they are connected to the Contact, which is great, however if the Client contact is attached to multiple Casework records then I see ALL emails when instead I just need to be able to see there the emails related to that Casework.

Therefore a simple tweak I need to be able to do is to add simple criteria rules to specify where to index which emails. 

For Example, on our older system: 
We generate a unique ID for all our Casework records, and when we email our clients regarding that specific case, the email subject header contains that unique ID.  So when any party replies to the thread (Client or Council Representative), if the system recognises the ID in the incoming emails subject header then that email gets indexed in the Casework record with that same ID. 

What I would ultimately need is: 

- Casework to display emails related to that record (Unique ID)
- Client Contact records to display ALL emails to/from that Client (regardless of Casework  ID)

- Council Representative records to display ALL emails to/from that Council Representative (regardless of Casework  ID)

Does anyone know if this is at all possible in Zoho as I can't currently see the options for such email rules? 
If it can't, is it possible to please request the feature? 

Again if not it would unfortunately force us to have to look elsewhere for a CRM.