What is a group mailbox?

A group mailbox (also called a shared mailbox) is an inbox that multiple people can access under one email address. Think support@yourcompany.com or orders@yourcompany.com. Everyone on the team can read incoming mail, send replies, and see what others have sent.

Why this matters for senders: group mailboxes often behave differently than personal mailboxes when it comes to authentication and tracking. When someone sends from a group mailbox, the From address might be the group address (support@) but the authentication often still checks against individual user credentials. If your DKIM signature doesn't align with the From domain, you'll fail DMARC and land in spam. The compliance angle: when you're using a group mailbox for customer support or sales, you need to be careful about how replies are tracked. If Alice and Bob both have access to sales@yourcompany.com and Alice replies to a customer, that reply needs to be logged somewhere Bob can see it (or you'll send duplicate responses). Most platforms handle this automatically, but if you're forwarding mail from a group address to individual inboxes, you lose that coordination.

Common setups: Google Workspace calls these "collaborative inboxes" or "groups." Microsoft 365 has both distribution lists (forward only) and shared mailboxes (shared inbox). The distinction matters because distribution lists don't let you see what others sent, but shared mailboxes do.

And if you're sending marketing email FROM a group mailbox address (like newsletter@yourcompany.com), make sure your ESP is authenticating correctly for that domain. Some ESPs will let you set a From address that doesn't match your authenticated domain, which will break delivery. Test it with our email header analyzer to see if your DKIM and SPF are actually passing.