# Email dictionary

> Reference tables for SMTP reply codes, enhanced status codes, email headers, DNS records and bounce categories, and how Emailit handles each one.

The email dictionary explains the codes, headers and records you run into when you send email. Use it when you're reading a bounce message, debugging an SMTP integration or publishing DNS records. Every page also says what Emailit does with each item, so you know whether to act.

## Reference pages

  - [SMTP reply codes](/docs/dictionary/smtp-reply-codes/): Three-digit server replies from 220 to 556, which ones Emailit retries, and the replies Emailit's own SMTP relay sends.
  - [Enhanced status codes](/docs/dictionary/enhanced-status-codes/): RFC 3463 codes such as 5.1.1 and 5.7.26, what they mean and how to fix them.
  - [Email headers](/docs/dictionary/email-headers/): From, Reply-To, Message-ID, DKIM-Signature, List-Unsubscribe and more, and which ones Emailit adds, rewrites or removes.
  - [DNS records](/docs/dictionary/dns-records/): MX, SPF, DKIM, DMARC, CNAME, PTR, BIMI, MTA-STS and TLS-RPT syntax with examples.
  - [Bounce categories](/docs/dictionary/bounce-categories/): Hard and soft bounces by cause, typical codes, how Emailit classifies them and what to do next.
  - [Glossary](/docs/glossary/): Short definitions of Emailit concepts and general email terms, from alignment to webhook secret.

## Where you see these values in Emailit

- **Email detail.** Open an email in **Email API → Emails** and check the **Deliveries** tab. Each delivery attempt shows the receiving server's full reply, including the reply code and enhanced status code.
- **Webhooks.** The `email.attempted` event includes `smtp_code`, `smtp_enhanced_code` and `smtp_response` for the failed attempt. See [Webhook event types](/docs/webhooks/event-types/).
- **Request logs.** Replies from Emailit's own SMTP relay, such as `535 Authentication failed`, appear in **Email API → Logs**. See [Request logs](/docs/logs/request-logs/).
- **Domain setup.** The exact DNS records Emailit asks you to publish are on the domain's **DNS Setup** tab. See [DNS records](/docs/domains/dns-records/).

## Related

- [Email statuses](/docs/logs/email-statuses/)
- [Bounces and complaints](/docs/deliverability/bounces-and-complaints/)
- [SMTP troubleshooting](/docs/smtp/troubleshooting/)

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Source: https://emailit.com/docs/dictionary/