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GlossaryUpdated

What is email deliverability?

Email deliverability is the ability of a sender to reach the recipient inbox rather than the spam folder or a rejection. It depends on authentication, sending reputation, list quality, complaint rates and message content. Delivery to a server is not the same as placement in the inbox.

Key facts

  • Google requires bulk senders to authenticate with SPF, DKIM and DMARC and to keep spam rates low. Source
  • Yahoo asks bulk senders to authenticate their domains and make unsubscribing easy. Source
  • DMARC.org describes how domain authentication and policy work together to protect a sending domain. Source

What deliverability means

This definition is part of the Mailprompt glossary. Deliverability is the practical ability to reach the inbox. It is not a single setting or a score. It is the result of authentication, reputation, list quality and the content of the message.

The word is often used loosely. A sender may say a campaign had good deliverability because few messages bounced, even when most of the delivered mail landed in spam. Bounces and placement are different measurements.

Authentication is the baseline

SPF, DKIM and DMARC tell the receiving server who is allowed to send for the domain and whether the message was signed. Google and Yahoo both ask bulk senders to authenticate. A domain without those records is starting from a disadvantage.

Authentication does not guarantee the inbox. It removes a reason for the receiving server to distrust the message. Reputation and engagement decide the rest.

Reputation is earned in small steps

A new sending domain has no history. Sending a large campaign on the first day is a reputation risk. A gradual ramp, starting with the most engaged recipients, gives the receiving servers a chance to observe a healthy pattern.

Reputation is also affected by complaints. A recipient who marks a message as spam is telling the provider that the sender is unwanted. A high complaint rate can outweigh good authentication. The fix is usually a smaller, more relevant audience, not a new domain.

The list is part of the system

A purchased list, an old list or a list with many hard bounces will hurt deliverability even when the content is good. The recipients did not ask for the mail, and the receiving servers can see the pattern.

List hygiene is not a one-time cleanup. Bounces, unsubscribes and inactivity accumulate. A regular review keeps the list closer to the people who want the mail.

Placement and measurement

Inbox placement is measured with seed lists or provider feedback, not with the delivery rate alone. The delivery rate tells you how much mail the server accepted. The placement rate tells you where it went.

A sender should look at delivery, placement, bounce rate and complaint rate together. A low bounce rate with a high complaint rate is not healthy. A high delivery rate with low placement is not success.

What to fix first

If authentication is broken, fix it first. If the list is old, clean it before the next campaign. If the complaint rate is high, reduce the audience and review the offer. If the volume is spiking, slow down.

Deliverability is not a trick that can be applied to a bad list. It is the cumulative result of sending mail that people asked for, from a domain they can recognize, at a volume the domain can support.

  • SPF authorizes the sending servers.
  • DKIM signs the message.
  • DMARC ties authentication to a policy and reports.

Frequently asked questions

Is deliverability the same as inbox placement?

No. Delivery means the recipient server accepted the message. Inbox placement means the message reached the inbox rather than the spam folder or a tab. A message can be delivered and still be filtered out of sight. The two numbers come from different sources.

What are the biggest factors in deliverability?

Authentication, sending reputation, list quality and complaint rates. A new domain with no history needs a gradual volume ramp. A domain with a high complaint rate needs a list and content review. A domain with broken authentication may be filtered before any of that matters.

How do I improve deliverability?

Authenticate the domain, remove hard bounces, stop mailing people who never engage, make unsubscribing easy and send content people asked for. Avoid purchased lists and sudden volume spikes. Check the complaint rate and the bounce rate together; a low bounce rate does not cancel a high complaint rate.

Sources