Pick the connection method that matches your provider. Every method produces the same thing: a mailbox (campaign) ready for Start Warm-Up.
All connect endpoints use
multipart/form-data, not JSON — send fields as form parts, withsnake_casenames.
| Provider | Use | When to pick it |
|---|---|---|
| Google Workspace / Gmail | Connect a Google Mailbox (OAuth) | You can run Google's consent flow and hold a refresh token. No app password needed. Invite-only — contact support to enable. |
| Google Workspace / Gmail | Connect a Google Mailbox (App Password) | Simplest Google path. Owner enables 2-Step Verification and generates a 16-character app password. |
| Microsoft 365 / Outlook | Connect a Microsoft Mailbox | Any Microsoft mailbox. Returns a consent URL; the mailbox stays pending until the owner authorizes. |
| Custom SMTP | Connect Mailbox with SMTP | Any provider without OAuth. You supply full SMTP and IMAP credentials. |
| SendGrid | Connect SendGrid Mailbox | SendGrid-relayed sending. |
| Any of the above | Get Secure Embed Form URL | You'd rather not handle credentials at all — Mailivery hosts the form, your users authorize there. |
Once connected, Start Warm-Up and then set volume and schedule — see Recommended Warm-Up Settings.