Deliverability guide
Sent is not delivered. What decides whether your email lands in the inbox — authentication, reputation and list hygiene — and what we handle for you.
Why "sent" is not "delivered"
An accepted API call means we queued your message, not that a human will see it. Between your send and the inbox stand two gates: authentication (can the mailbox provider prove the message is really from you?) and reputation (does it trust the source enough to skip the spam folder?). Get both right and delivery is boring — which is exactly what you want.
Authentication: SPF, DKIM, DMARC and reverse DNS
Authentication is table stakes. Without it, major providers quietly send you to spam or reject outright. Four records do the work, and we walk you through the first three when you verify a domain:
| Record | What it proves |
|---|---|
| SPF | This server is allowed to send for your domain. |
| DKIM | The message was signed by your domain and not altered in transit. |
| DMARC | What to do when SPF or DKIM fails — and where to send reports. |
| Reverse DNS (PTR) | The sending IP resolves back to the sending host: a forward-confirmed identity. |
The PTR record is ours to run, not yours — and we run it: our own MTA sends from an IP with forward-confirmed reverse DNS, so providers can verify the source before they even read the message. You handle the domain-level records; we handle the infrastructure underneath.
Reputation and warm-up
Reputation is earned by sending mail people want and avoiding mail they do not. A brand-new sender has no history, so start slow: send to your most engaged recipients first, grow volume gradually over days, and let positive engagement build before you scale. A sudden spike from an unknown source is the classic spam signal.
- Keep transactional and marketing on separate identities — promotional complaints must never taint your receipts and one-time codes.
- Send to people who asked. Purchased lists and stale addresses generate bounces and complaints, which are exactly what reputation punishes.
- Grow volume in steps, not jumps. Doubling every day or two is healthier than 10× overnight.
Bounces, complaints and list hygiene
A hard bounce means the address is dead; a complaint means the recipient marked you as spam. Both are added to your suppression list automatically, and we refuse to send to a suppressed address before the message leaves the queue — sending to dead addresses is the fastest way to wreck a reputation that does not roll back.