Mailbox providers judge you on how your last send went. Validating a list before you use it removes the addresses that would have counted against you — and tells you honestly when an address can’t be settled.
What a bounce actually costs you
A hard bounce isn’t a failed delivery — it’s a signal to the receiving provider that you don’t know who’s on your list. Enough of those and your good mail starts landing in spam, or nowhere at all.
Bounces are on your record
Providers keep score per sender. Dead addresses in a list you bought a year ago still cost you today.
Spam traps punish volume
Some addresses exist only to catch senders who don’t clean their lists. One is enough to change how a provider treats you.
Checking sends nothing
Resenty inspects an address without delivering a message to it, so validating a list can’t hurt the reputation you’re protecting.
In plain language
Every address comes back as one of six verdicts. Some are decisions you can act on straight away; others are honest descriptions of what the mailbox would — or wouldn’t — tell us.
Deliverable
KeepThe domain accepts mail and the mailbox exists. Send with confidence.
This is the segment you mail.
Undeliverable
RemoveThe mailbox doesn’t exist, or the domain can’t receive mail at all. Sending here is what produces a hard bounce.
Don’t hold it for a second attempt later.
Risky
SegmentThe address resolves, but something about it argues against mailing: a role account like info@, or a signal of a complainer or a trap. Reachable isn’t the same as worth sending to.
Mail cautiously, or leave it out of high-volume sends.
Accept-all
SegmentThe domain answers yes to every address, so no service can confirm this particular mailbox. We label the domain rather than guess at the address.
Why this can’t be resolved from outside is explained below.
Disposable
RemoveThe address belongs to a temporary or burner mail provider, the kind people use once to get past a signup form.
Throwaway domains churn — today’s inbox is tomorrow’s bounce.
Unknown
RefundedThe mail server didn’t give us a usable answer — it timed out, throttled the check, or refused to confirm. We say so instead of picking the likelier answer for you.
The credit goes back automatically. Re-check later if you like.
Some servers say yes to everything
A normal mail server will tell you whether a particular mailbox exists. An accept-all — sometimes called catch-all — server answers yes to every address at the domain, whether or not anyone reads it. Companies configure it that way on purpose: to catch typos, to avoid leaking their staff directory, or because a security gateway sits in front of the real mailboxes.
When that’s the answer, no verification service can tell the difference from outside. We label the domain accept-all and tell you what that means, rather than dressing a guess up as a verdict.
We’d rather refund the credit than guess
If a mail server won’t give us a usable answer, the result comes back as unknown and the credit for that address is returned to your balance automatically — no ticket, no request. A guess that reads like a verdict is worse than no verdict: you’d act on it, and your reputation would pay for it.
Every result carries the reason behind it, so you can see which signal decided the verdict instead of taking our word for it. The accept-all and unknown guide walks through the cases one by one.
See what your list actually looks like
Run a sample and read the verdicts yourself — nothing is sent to anyone on it. Every new account starts with 100 free credits, no card required.
Start free