Here is a video on how to set master inbox up and its features: https://www.loom.com/share/2824779a489343dc97e9482118e7a8c5
Case 1 :
IF prospect replies to an email sent from your mailbox, then if you simply hit "reply" or "reply all" from master inbox, the email will always be sent in guise of your mailbox and not master inbox.
Case 2 :
If you receive a message to any of your mailboxes (the Prospect was the initiator), then if you simply hit "reply", the response will come from the Master Inbox (Ρ Ρ Ρ Ρ @maildoso.email).
However, if you hit "reply to all" (or add the address of the mailbox in question as the second recipient), the email will be visible as sent from that address.
Case 3 :
Finally, if you want to write to someone from master inbox , you can in "To:" field enter the destination email and your maildoso mailbox connected to that master inbox. When you hit send, it will be sent from the maildoso mailbox and not master inbox.