Mailboxes
Senders.
Connect mailboxes that send your campaigns. Use Resend for high-volume infra (recommended for cold email at scale on a sister domain). Use Gmail OAuth for low-volume "from your real inbox" sends — better for sequences sent off your primary identity, capped low on purpose for deliverability.
Add sender
API key
Resend
Best for cold email volume on dedicated sister domains. Set up SPF/DKIM/DMARC on your sending domain, verify it in Resend, then paste the API key.
OAuth
Gmail
Sends through your real Gmail. Authenticate once, we handle refresh + reply detection. Limit kept low (8/hr · 30/day) to protect deliverability.