Any amoCRM user can connect to a personal mailbox. When you receive an email, you will not create an application in "Unhandled". But if there is a contact in the system with the email address of the sender, the letter will be displayed in the card. Only the owner can send letters from such a mailbox.
It can give access to view the mail to the account administrator by ticking the Mail settings.
Also, he can give access to view the letter (one letter at a one time) for all users at once. You can do this from the Lead / Contact / Company card by clicking on the lock icon next to the letter.