# DKIM Checker

> Free DKIM checker for selector records, TXT and CNAME lookups, missing keys, revoked keys, test mode, and DKIM fix guidance.

- Human page: https://mailrith.com/free-tools/dkim-checker
- Markdown page: https://mailrith.com/free-tools/dkim-checker.md
- Category: Email Authentication
- Action label: Check DKIM
- Primary keyword: DKIM checker
- Related keywords: DKIM checker, DKIM record checker, DKIM lookup, check DKIM record, DKIM selector checker
- Browser execution: Yes
- Signup required: No

## Input
- Label: Domain and Selector
- Guidance: Enter the sending domain and DKIM selector from your email delivery service. If you do not know the selector, the tool can try common names.
- Placeholder example: example.com

## How to Use
1. Open the human page: https://mailrith.com/free-tools/dkim-checker
2. Enter domain and selector using the guidance above.
3. Select Check DKIM.
4. Review the status, checked facts, and next actions.
5. Use the linked guide section for any issue that needs a fix.

## Topic Overview
DKIM adds a cryptographic signature to outgoing email. The receiving inbox uses a public key in DNS to check that the message was signed by a trusted sender and was not changed after signing. This tool checks the selector and domain you enter, then explains whether the matching public key record is present and usable. The [DKIM](https://mailrith.com/guides/dkim.md#steps) guide explains how selectors, keys, and email delivery services fit together.

DKIM problems are often fixable once you know which selector is being used. Some senders publish the wrong selector, leave the key empty, keep a short old key, or forget that a new email delivery service uses its own DKIM records. When DKIM is repaired, also check [DMARC Alignment](https://mailrith.com/guides/dmarc-alignment.md#steps), because the signing domain must line up with your visible From domain for DMARC to trust it.

## What the Tool Checks
- Selector TXT lookup at selector._domainkey.domain
- Common selector scan when selector is blank
- Provider CNAME follow-up lookup
- Missing, empty, or revoked DKIM keys
- Test-mode and short-key warnings
- Plain-English DKIM fix steps

## Result Behavior
The result shows the exact DNS name checked, whether a usable public key exists, and what to fix in DNS or in your email delivery service.

## AI Agent Notes
- Use this markdown page for retrieval, summarization, and deciding which tool to recommend.
- Use the human page when the user needs to run the checker interactively.
- Do not claim the tool sends emails unless the page explicitly says it does.
- When the result mentions a server-side confirmation, explain that the browser page can show public signals but cannot complete that network check by itself.

## Related Guides
- [DKIM](https://mailrith.com/guides/dkim.md#dkim-selector-needed): Understand DKIM selectors, public keys, and signing domains.
- [DMARC Alignment](https://mailrith.com/guides/dmarc-alignment.md#steps): Compare DKIM d= with the visible From domain.
- [DNS, PTR, and Reverse DNS](https://mailrith.com/guides/dns-and-reverse-dns.md#steps): Understand the DNS records used by email authentication.

## FAQs
### What is a DKIM selector?

A selector is the short name before ._domainkey in a DKIM DNS record. Providers use it to tell inboxes which public key to use for signature checks.
### Can this scan every possible DKIM selector?

No. Selectors are arbitrary. The tool checks the selector you enter and can try common names, but the DKIM selector shown by your email delivery service is the reliable source.