How does your company handle e-mail in erpnext?

I am trying to set up email in the best way and need some real-world advise:
1- Do you handle ALL your company email within erp-next?
1a- How much do you still need to use your email client?
2- Do you handle just a subset of emails in erpnext? (eg. only customer support emails) If so what is handled by erpnext (or not) and why?
3- Other tips, best practices, etc?

Refer [8.0] Email Inbox merged - WIP