What Is Email Deliverability?

Three inputs, in ascending order of weight. Authentication is the gate: SPF, DKIM and an aligned DMARC result tell the receiver the message is really from the domain it claims. Infrastructure is the next layer: the sending IP, its PTR record, and whether either the IP or the domain appears on a blocklist the receiver consults.

Recipient behaviour outweighs both. Replies, moves out of spam and deletions without reading are the signals a provider trusts most, because they come from its own users rather than from anything a sender can publish. This is why two senders with identical DNS can get opposite outcomes at the same provider.

Delivery rate counts messages the receiving server accepted. Deliverability asks where those accepted messages went. A message filed straight into spam was delivered by any sending log you look at, which is why a clean sending report is compatible with a campaign nobody saw.

The practical consequence is that deliverability cannot be measured from the sending side alone. It takes seed mailboxes at the providers you send to, or a provider dashboard such as Google Postmaster Tools, to see placement rather than acceptance.

Authentication, sending volume and ramp, and who is on the list. Those are the levers, and the third is the strongest: a verified list of people with a plausible reason to reply produces the engagement that drives everything else, and no DNS configuration compensates for a list that does not.

What a sender cannot control is the filtering model, which is proprietary and changes without notice. Treat published provider requirements as the floor rather than the strategy.