Email Validation
Disposable Email Detection Guide
Plan disposable email checks as a product policy layer instead of confusing them with basic email regex validation. This reference is written for developers who need practical validation behavior, reviewable rules and safe examples rather than copied snippets with no explanation.
Recommended workflow
| Step | Why it matters |
|---|---|
| Separate policy from syntax | Disposable-domain blocking is a business rule, not an email format rule. |
| Use reviewable lists | Domain deny lists need source, date and a rollback path. |
| Avoid silent rejection | Tell legitimate users what changed and how to contact support. |
| Watch false positives | Shared domains, aliases and privacy services can be legitimate. |
Starter snippet
email syntax -> normalize domain -> policy list check -> verification -> risk reviewReview checks
- Keep allowlist overrides for trusted partners.
- Version domain lists so support can explain decisions.
- Do not expose internal risk scores to the browser.
- Review conversion impact after policy changes.
Common mistakes
- Blocking whole providers without measuring legitimate usage.
- Mixing anti-abuse logic into a reusable regex helper.
- Using copied domain lists with no maintenance owner.
Validation should help users correct input while protecting systems from bad data. Keep syntax checks, product policy, security review and deliverability checks separate.
Related Formalint references
Continue with Email Domain DNS Validation, Secure Cookie Checklist, Secrets Redaction Checklist.