SieveStop bouncing. Clean every email list before you send.
Sieve verifies addresses with a real SMTP conversation and audits your sending domain, so your campaigns reach real inboxes, not spam traps.
Free forever tier · No credit card · Unlimited DNS checks plus 100 live SMTP verifications a month
This pipeline held our own campaign bounce rate under 1%; anything under 3% is considered healthy.
Will your email reach the inbox?
Grade any sending domain A to F in seconds: MX, SPF, DKIM, DMARC and the major blacklists, with exact fixes for whatever we find.
Try:stripe.comgithub.comsievemails.comWe only read public DNS records.
From raw list to safe send
One account covers the quick single check, the 10,000-row cleanup, and the domain audit in between.
Single validation
Run one address through the full 8-layer pipeline and see every verdict with a confidence score.
Bulk validation
Paste or upload a list, then export a clean / risky / rejected breakdown as CSV when it's done.
Deliverability audit
Score a sending domain A to F across MX, SPF, DKIM, DMARC and blacklists before you hit send.
Private by default
Uploaded lists are encrypted at rest, isolated to your account, and deletable any time.
Every address, fully scrutinized
Each email runs through eight independent checks across three phases. When live SMTP probing is available we verify the mailbox directly; otherwise we fall back to a thorough DNS-only analysis. You always get a transparent, layer-by-layer breakdown.
- 1Syntax & normalization
- 2Typo & domain suggestion
- 3Disposable detection
- 4Role-address flagging
- 5MX record lookup
- 6SMTP mailbox probe
- 7Catch-all detection
- 8Auth & blacklist signals
Evidence, not guesses
Most verifiers hand you a label. Sieve shows its work, so you can defend every send.
Verdict receipts
Every address comes back with evidence: the MX host we spoke to and the exact SMTP reply, not just a colored label you have to take on faith.
Catch-all confidence
Catch-all domains get a scored confidence instead of a shrug, so half your list stops hiding behind the word unknown.
Honest by default
When a mailbox cannot be probed live, we say so and show the DNS-only verdict, instead of dressing a guess up as a fact.
How big is your list?
Credits never expire and every one of them runs the same live SMTP probe as Pro.
Credits, not commitments
- Same live SMTP verification as Pro
- API access included
- No subscription, use them whenever
- Volume discounts built into the packs
Verifying every month? Pro is $29/mo with 15,000 live verifications included.
Clean your list before the next send
- Free forever tier, no credit card
- A verdict receipt for every address
- Encrypted at rest, delete anytime