Guide

OTP email testing in CI: a practical guide

Email is slow and asynchronous, which is why email tests flake. A few rules make them dependable.

Updated 2026-10-02 · Emailsify

Rules that remove flakiness

  1. One inbox per test. Never share addresses between tests.
  2. Wait for the message, never sleep for a fixed time.
  3. Set a timeout that reflects real delivery times, then fail with a useful message.
  4. Filter by sender or subject so stale mail cannot match.
  5. Assert on the extracted code or link, not on the whole email.

What to log

  • The generated address.
  • The time you triggered the email and the time it arrived.
  • The subject of the message you matched.

Frequently asked questions

What timeout should I use?

Start with 30 to 60 seconds and tune from your measured delivery times.

Keep reading

Email OTP vs magic linkOne-time codes and magic links both prove you own an address. How each works, their trade-offs and how to test them.Verification email not arriving: how to fix itWhy a verification code or link never shows up, and a checklist for getting it to arrive, for temporary and normal inboxes alike.How long do verification codes last?Typical lifetimes of email verification codes and magic links, why they are short and what to do if yours has expired.