Testing emails before sending is a release-control process, not a last-minute spot check.

## Quick preflight sequence

1. Validate sender authentication (SPF, DKIM, DMARC).
2. Verify template quality and spam-risk signals.
3. Test rendering across target clients.
4. Test links, buttons, and dynamic fields.
5. Run end-to-end send-and-receive workflow checks.
6. Gate launch on pass/fail outcomes.

## What to test before every send

### 1. Sender identity and authentication

Run these first because every other check can be invalidated by auth failures.

- [SPF checker](/tools/spf-checker/)
- [DKIM checker](/tools/dkim-checker/)
- [DMARC checker](/tools/dmarc-checker/)
- [DNS lookup](/tools/dns-lookup/)

### 2. Spam-risk and content hygiene

Check for patterns that reduce inbox placement.

- Suspicious link patterns
- Missing plain-text part
- Overweighted image-to-text ratio
- Subject/body mismatch

Tooling:

- [Email spam checker](/tools/email-spam-checker/)
- [Email header analyzer](/tools/email-header-analyzer/)

### 3. Rendering and client behavior

Ensure your email is readable on your core audience clients.

- Primary desktop clients
- Gmail and Outlook web
- Mobile clients for top user segments

Use [Email client testing](/testing/email-client-testing/) for the compatibility checklist, then run [device previews](/product/device-previews/) when the final delivered email needs Gmail, Outlook, mobile, desktop, light-mode, and dark-mode evidence.



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### 4. Link and action integrity

Validate every high-impact CTA path.

- UTM correctness
- Expiration behavior for links/tokens
- Fallback/error pages
- Tracking and compliance parameters

Use: [Campaign testing](/testing/campaign-testing/)

### 5. End-to-end workflow validation

Trigger real app behavior and verify message outcomes.

- Account verification
- Password reset
- Billing notifications
- Security alerts

Use:

- [Email Sandbox](/product/email-sandbox/)
- [Email Integration Testing](/product/email-integration-testing/)

## Pre-send release gate template

| Check group             | Owner                | Pass criteria                                      |
| ----------------------- | -------------------- | -------------------------------------------------- |
| Auth checks             | Platform/infra       | SPF, DKIM, DMARC pass and aligned                  |
| Spam and header quality | Deliverability owner | Spam-risk threshold met, header anomalies resolved |
| Rendering checks        | Design/marketing     | No blocking defects on target clients              |
| Link and CTA checks     | Campaign owner       | All primary CTAs and tracking parameters valid     |
| Workflow tests          | QA/engineering       | Critical flows pass in CI and staging              |

## Good process vs bad process

Good process:

- Uses named owners and explicit pass criteria
- Runs the same checks every send cycle
- Blocks sends when high-risk checks fail

Bad process:

- Manual preview only
- No authentication verification
- No workflow assertions for dynamic content

## MailSlurp implementation pattern

1. Capture outgoing messages in isolated inboxes.
2. Assert content, links, and codes automatically.
3. Pair with deliverability and auth checks.
4. Publish pass/fail status before send approval.

Start with:

- [Email deliverability audit checklist](/guides/email-deliverability-audit-checklist/)
- [Email deliverability test](/testing/email-deliverability-test/)
- [Email testing API](/developers/email-testing-api/)