Your Master Inbox brings replies from your SMTP mailboxes into one place. Here's a short video on how to set it up and use it, followed by exactly how the sender is chosen when you reply.

Video walkthrough: how to set up and use the Master Inbox.

Case 1 — a prospect replies to an email you sent. If you hit Reply or Reply all from the Master Inbox, your message always goes out as your original mailbox — not as the Master Inbox.

Case 2 — a prospect writes to your mailbox first (they started the thread). If you simply hit Reply, the response comes from the Master Inbox (xxxx@maildoso.email). If you instead hit Reply all (or add the mailbox in question as a second recipient), the email shows as sent from that mailbox.

Case 3 — you're starting a new message from the Master Inbox. In the To: field, enter the destination email and the Maildoso mailbox connected to that Master Inbox. When you send, it goes out from that mailbox, not the Master Inbox.

To set forwarding and understand SMTP vs. Google Workspace behaviour, see Forwarding Addresses / Master Inbox. If warmup emails are cluttering your Master Inbox, see Warmup Filters. If a reply seems missing, see Not getting emails forwarded to Master Inbox.