Core Concepts
Mailboxes
The inboxes a campaign sends from and receives replies in.
A mailbox is one of your connected inboxes — the email account a campaign sends from and receives replies in.
A campaign sends from one or more mailboxes. Spreading sends across several mailboxes keeps volume per inbox lower, which helps deliverability.
You pick which mailboxes a campaign uses by their ids. List your connected mailboxes with GET /v1/mailboxes to get those ids.
Tags let you group mailboxes (for example, by domain or team) so you can find and assign them more easily.
You will use a mailbox id in the first step of the Campaign setup guide. Full fields are in the API Reference.