A message can be accepted by a server and still never be seen. Deliverability is the word for the gap between those two outcomes.
Delivery is not deliverability
| Term | Question it answers |
|---|---|
| Delivery | Did the receiving server accept the message? |
| Deliverability | Did it reach the inbox, where a person could read it? |
A 99% delivery rate is compatible with half your mail going to spam. The first number comes from your sending platform. The second you have to infer.
What decides it
Mailbox providers weigh several things, and they do not publish the formula.
- Authentication. SPF, DKIM and DMARC that pass and align.
- Reputation. The track record of your domain and your IP addresses.
- List quality. How many addresses bounce, complain or never engage. See bounce rate and complaint rate.
- Engagement. Whether recipients open, click, reply or delete without reading.
- Content and behaviour. What you send, how often, and whether volume changes suddenly.
Deliverability on Amazon SES
SES is infrastructure. It sends your mail and reports what happened to it, but it does not manage your list, warn you about drifting rates or tell you when a DNS record broke. Those parts are yours. AWS adds one hard rule on top: if your bounce or complaint rate climbs too high, your account is put under review and sending can stop.
A useful habit
Treat deliverability as something you watch, not something you set up. The causes of a drop are usually slow: a list that aged, a record that changed, a campaign that went to the wrong segment. See email deliverability monitoring.
Common questions
Is delivery rate the same as deliverability?
No. The delivery rate counts messages the receiving server accepted. A message in the spam folder was delivered, but it was not deliverable in the sense that matters.
Can I measure inbox placement with Amazon SES?
Not from the plain SES events, which report delivery and not the folder. AWS's Virtual Deliverability Manager describes inbox placement rates and testing in its global deliverability features, and Google Postmaster Tools shows how Gmail sees your domain.