How to organize the work of managers with corporate mail?

Question

Email

Good afternoon!
Our company is located in Tanzania (East Africa), we organize expeditions to Kilimanjaro and safari trips, now we have 9 managers in our staff, and the question arose of optimizing email correspondence with clients.
At the moment we are using corporate mail tied to gmail.com in conjunction with CRM Streak, it looks like this:

This mini-CRM allows you to split your work gmail mail into several desktops and track the status of communication with the client / his first and last name / fill in the basic information + automatic filters put down asterisks, names and it is immediately clear by the color of the star whose client this is. But with the growth in the number of employees, difficulties began to arise when one mail is used for all managers.
It is also not entirely rational to allocate personal mail to everyone, we regularly go on trips / expeditions, and daily responses to clients are critically important in our field.
What I am looking for, but so far unsuccessfully, maybe the owners of their own businesses or IT specialists will tell you in which direction to look:
1. Most likely, you need a comfortable email client with the ability to automatically put labels, for example, a client wrote to us from [email protected] , we made a label that this is a client of Valeria's manager named Ivan Kozhedub, and when a letter arrives again from this mail, we automatically see the labels Valeria / Ivan Kozhedub / Kilimanjaro / April 2015 (this is just an example)
2. I considered options for integrating mail with a ticket system, but here we run into possibilities - in Tanzania the Internet is rather slow (about 1-5 Mbps, and given that all servers are located in Europe / Russia, the connection is really not fast) + regular power outages. It would be much more comfortable to have an email client with the ability to write letters offline. I planned to use Thunder Bird from Mozil, but so far I don’t see the opportunity to implement my idea, voiced in paragraph 1.
If someone can tell me where to dig, or help / set up, I’m ready to thank you well in monetary terms)

Answer 1

try
https://chrome.google.com/webstore/detail/gmail-of...
and
accordingly,
it should help with tags ,
but how it will be synchronized with different computers - you need to look