Email verification fails more often than people think

Email verification looks simple on the surface, but in practice it fails more often than many teams expect.

From what I have seen, most issues are not caused by the email service itself, but by how verification systems are designed and tested.

Common failure points:

• Domains that are silently blocked

• Messages delayed just long enough to expire

• OTP codes with very short lifetimes

• Rate limits that are easy to hit during retries

• Users refreshing or resubmitting forms too quickly

In many cases, verification links are far more reliable than OTP codes, especially for non-critical accounts.

Curious how others here test or design their email verification flows. What issues have you run into?