# Email deliverability

> The ability to reach the part of the mailbox where a wanted recipient can find and act on an email.

- **Category:** Deliverability
- **Updated:** July 2026
- **Canonical page:** [https://emailbump.com/glossary/email-deliverability](https://emailbump.com/glossary/email-deliverability)

## Definition

Email deliverability describes the outcome after a message is sent: whether mailbox providers accept it, where they place it, and whether the intended recipient can realistically find it. A delivered message can still land in spam, so delivery rate and deliverability are related but not interchangeable.

Deliverability is not a single score. It emerges from authentication, domain and IP reputation, recipient permission, engagement, complaints, content, infrastructure, volume patterns, and each receiver’s private filtering decisions.

## Why it matters

A campaign cannot create value if customers never see it. Deliverability also compounds: poor acquisition or weak targeting creates complaints and disengagement, which can make later mail harder to place even when that later message is useful.

## How it works

1. The sending system connects to the recipient’s mail server and attempts delivery.
2. The receiver evaluates the connection, IP, domains, authentication, message structure, content, and historical behavior.
3. The receiver can reject, temporarily defer, accept to spam, accept to another tab, or place the message in the inbox.
4. Senders combine event data, complaint feedback, authentication reports, Postmaster Tools, and controlled seed tests to diagnose the outcome.

## Example: Delivery is not placement

```text
10,000 attempted
   100 rejected or bounced
 9,900 accepted by receiving servers  → 99% delivery rate
 8,600 estimated inbox placement      → 86.9% of delivered
 1,300 estimated spam/other placement
```

## Common mistakes

- Calling a high acceptance rate proof that mail reached the inbox.
- Looking at one blended metric instead of splitting results by receiving domain and stream.
- Treating copy changes as a substitute for permission, list health, authentication, and stable sending.
- Making abrupt volume or identity changes without establishing history.

## Key takeaways

- Measure acceptance, placement, and recipient response as distinct layers.
- Protect permission and complaint rate before optimizing small technical details.
- Diagnose by mailbox provider, domain, stream, and time period.

## Related definitions

- [Inbox placement](https://emailbump.com/glossary/inbox-placement.md) — Where accepted email is placed, such as the primary inbox, another inbox tab, spam, or junk.
- [Sender reputation](https://emailbump.com/glossary/sender-reputation.md) — A receiver-specific assessment of sending identity and behavior used when filtering email.
- [Email authentication](https://emailbump.com/glossary/email-authentication.md) — The DNS and cryptographic mechanisms receivers use to verify sending identities and domain authorization.
- [Spam complaint](https://emailbump.com/glossary/spam-complaint.md) — A recipient signal that a message is unwanted, usually created by marking it as spam or junk.

## Related guides

- [How to A/B test email service providers without fooling yourself](https://emailbump.com/blog/ab-test-email-service-providers.md) — A rigorous guide to ESP evaluation: experimental design, reputation confounders, delivery and latency metrics, webhook reliability, failover, cost, and migration.
- [Gmail reputation-based bounces: diagnose, contain, and recover](https://emailbump.com/blog/gmail-reputation-bounces.md) — An incident guide to Gmail 4.7.x and 5.7.x responses, sender-level classification, safe retries, Postmaster Tools, abuse containment, and reputation recovery.
- [How to check your email domain reputation—and improve it](https://emailbump.com/blog/check-email-domain-reputation.md) — A practical guide to authenticated sending domains, Google Postmaster Tools, reputation signals, investigation workflows, stream separation, and recovery.
- [Email bounces: how to classify, retry, suppress, and recover](https://emailbump.com/blog/email-bounce-handling-guide.md) — A practical operating guide to SMTP failures, enhanced status codes, retries, suppression, webhooks, and the product workflows that protect sender reputation.
- [Why customers mark transactional email as spam—and how to stop it](https://emailbump.com/blog/reduce-transactional-email-spam-complaints.md) — An operational guide to expectation, message purpose, notification controls, duplicate prevention, form abuse, suppression, and complaint monitoring.
- [The email deliverability checklist for every campaign](https://emailbump.com/blog/email-deliverability-checklist.md) — A practical pre-send routine for protecting your sender reputation and reaching more inboxes.
- [Google Postmaster Tools in 2026: the dashboards that matter](https://emailbump.com/blog/google-postmaster-tools-guide.md) — A practical guide to the new compliance view, spam-rate signals, authentication data, delivery errors, feedback loops, and the Postmaster Tools v2 API.

## Primary sources

- [Google: Email sender guidelines](https://support.google.com/mail/answer/81126?hl=en)
- [M3AAWG: Sender Best Common Practices](https://www.m3aawg.org/sites/default/files/doc_files/M3AAWG_Senders_BCP_Ver3-2015-02.pdf)