Where to find the sent emails from a shared mailbox

Where to find the sent emails from a shared mailbox

Hi,

actually I want to have a mail account like info@mycompany.com as the central point of contact with customers. I already switched from distribution list to shared mail box. But I still don't understand how to use it the right way, so that also my colleagues within the same group / shared mailbox, also have the full overview what mails have been sent to the customer. 

I thought the app "Teaminbox" is the correct one, but there I cannot find it either.
I also tried to have all mails in the CRM details from the contact, but I'm not able to setup the info@mycompany.com in the "E-Mail" part of the seetings. It's possible in the "organisation-Mail" part, but this doesn't help.

So what is the best way to have a good overview for all team members about all incoming and sent mails?

Thanks
Patrick