You may notice that a recipient sees a different one of your domains than expected, or that replies seem to come back through a different mailbox. This is our intelligent mailbox rotation, and it's intentional. (If you're trying to rule out a real problem rather than rotation, see the fuller checklist in My emails are sending from the wrong domain or address.)

To keep mailboxes healthy, we rotate and filter sending behind the scenes while preserving the sender experience. The lead receives the email normally, and if they reply, the response is automatically routed back to the original mailbox it was sent from.

Nothing changes operationally for you, and the lead notices nothing. The goal is to prolong mailbox health, reduce strain, and let the infrastructure self-heal.

Rotation works best, and leans least on any single domain, when two things are set up on your account: a redirect URL on your domains, and your Master Inbox. Without them, rotation has less healthy capacity to work with and can lean harder on the domains that aren't fully configured. See Domain redirects: what they do and how to set your redirect URL and Using your Master Inbox and connecting mailboxes to an email app to check both are set up on your account.