What happens when I verify an email I already verified recently?

There is no caching layer between you and the verification engine. When you submit an address that was checked an hour ago or a minute ago, Valid Email Checker runs the full 11-step verification fresh, contacts the mail server again, charges one credit, and returns a result based on the live response. The system does not look at the prior verification, does not warn you that you just ran this one, and does not give the credit back if the second result matches the first.

This is a deliberate choice. Email verification is point-in-time — mailbox state changes, providers shift their anti-probe defences, greylisting decisions update. Honouring a cached result would mean returning stale data when the customer asked for a current check, which would undermine the 99%+ accuracy commitment.

How the dashboard surfaces past verifications

The bulk task history (and your verification results table) keeps every result you have ever produced. If you want to see whether an address was checked before, that record is searchable. But the Single Email Verifier on the dashboard does not auto-look-up prior results before deciding to run — it always runs.

For the API, the same rule applies: every call to the single-verification endpoint runs fresh through the engine. If you want to deduplicate before making the call, do that on your side by looking up the address in your own database first.

Why no caching at all

• Mailbox state changes faster than expected. Even a 24-hour cache would return stale data for any mailbox that disabled overnight or filled up overnight.
• A cache hit looks identical to a real verification from the customer side, but produces no fresh provider check. Letting that happen silently would weaken the accuracy guarantee.
• The right place to deduplicate is on the customer side, where you know the freshness requirements of your own workflow. Some use cases need verification every hour; others tolerate a month-old result.
• Credits per verification are already small. The cost of a quick re-check is in the cents; over-engineering a cache to save the cost rarely pays off.

When you should re-verify versus reuse a prior result

If the prior result is less than a week old and was a definitive Safe or Invalid, reusing it is fine. If the prior result was Catch-All, Risky, Inbox Full, or Unknown, the underlying conditions are likely to change quickly and re-verification within 7 to 14 days is worth it. For the broader cadence question see how often should I clean my email list.

For cold outreach, the rule of thumb is to verify within 48 hours of the send. For newsletters to engaged subscribers, monthly is usually enough.

No-cache and the Unknown refund

One nuance: when a verification returns Unknown, the credit is auto-refunded. If you immediately re-run the same address and it returns Unknown again, you also get that second credit refunded. So in the specific case of a stubbornly-unverifiable address, repeated attempts cost nothing beyond your time. See can I re-run a failed verification for free for the Unknown auto-refund mechanic in detail.