Bad data in Mailshake tanks your deliverability across all campaigns. BounceZero cleans your list before it enters Mailshake - so every campaign starts from a clean slate.
Mailshake sends from your own mailbox. Every hard bounce hits your domain reputation directly - and one bad list can poison every campaign that follows.
Mailshake pauses campaigns that exceed bounce thresholds, but the reputation damage is already done. Gmail and Outlook remember your bounce history at the domain level, so one dirty list drags down reply rates across all future sequences.
Around 22% of B2B email addresses go stale every year as people change jobs. That prospect list you exported six months ago is already full of dead mailboxes waiting to bounce inside your Mailshake sequence.
Roughly 23% of B2B domains are catch-all - they accept every address, valid or not. Basic checks pass them; the bounces arrive later. BounceZero uses 3-probe catch-all analysis to separate real mailboxes from silent traps.
Every email in your list runs through the full BounceZero pipeline - up to 99.8% accuracy in internal testing on SMTP-verifiable addresses versus the industry benchmark of ~95%.
We connect to the receiving mail server and confirm the exact mailbox exists - before Mailshake ever attempts delivery.
3-probe analysis distinguishes genuinely deliverable addresses from catch-all domains that accept everything and bounce later.
Flags info@, sales@ and admin@ addresses - the ones that rarely reply and frequently report cold outreach as spam.
Catches temporary and throwaway domains that inflate your list size while contributing zero pipeline.
Confirms the domain actually has mail servers configured - dead domains are removed before they hard-bounce.
Identifies known and suspected spam trap patterns that get sender domains blacklisted after a single Mailshake send.
Five minutes of cleaning protects weeks of campaign performance. Here’s the workflow Mailshake users run before every new sequence.
Pull your leads as CSV - from Mailshake, your CRM, LinkedIn scraper, or wherever your prospect data lives. One column of email addresses is all BounceZero needs.
Drag your CSV into the BounceZero dashboard. Dashboard jobs up to 1,000,000 addresses are supported, and a typical 10K prospect list processes in 5-10 minutes.
Every address is verified for mailbox existence, catch-all status, role accounts, disposable domains, MX records, and spam traps - at up to 99.8% accuracy in internal testing on SMTP-verifiable addresses.
Export only the addresses marked Deliverable. Risky, unknown, and invalid addresses stay out of your outreach - and out of your bounce stats.
Upload the cleaned CSV as your Mailshake recipient list and launch your campaign knowing every send has a real mailbox behind it - typically under 0.5% bounces.
Building your own lead pipeline? Verify addresses in real time with our email verification API - provider-dependent response time.
Replacing a blacklisted sending domain means new domain costs, weeks of warm-up, and lost pipeline. Verification costs $3 per 1,000 emails.
Want the exact numbers for your list size? Try the ROI calculator.
Common questions from Mailshake users about verifying lists with BounceZero.
BounceZero works alongside Mailshake through a simple CSV workflow: export your prospect list, verify it in BounceZero, and import the clean file back into Mailshake as your recipient list. Because Mailshake accepts standard CSV imports, no plugin or connector is required - and if you build custom lead pipelines, the BounceZero API (provider-dependent response time) lets you verify addresses in real time before they ever reach Mailshake.
Always before. Mailshake sends from your own mailbox, so any hard bounce counts against your domain reputation the moment it happens. Verifying first means invalid addresses never enter a sequence, keeping your bounce rate typically under 0.5% and preventing Mailshake from pausing campaigns for exceeding bounce thresholds.
A 10,000-email list processes in about 5-10 minutes through bulk upload, and dashboard jobs up to 1,000,000 addresses are supported. Most users verify their list right before importing to Mailshake, so cleaning adds only a few minutes to campaign setup.
Yes - around 23% of B2B domains are catch-all, meaning they accept mail for any address and bounce it later. BounceZero uses 3-probe catch-all analysis to determine which addresses on those domains are genuinely deliverable, instead of simply marking the whole domain as "unknown" like basic verifiers do.
Your list gets smaller, but your results get bigger. With roughly 22% of B2B addresses decaying every year, a portion of any list is already dead weight that only generates bounces and spam-folder placement. Sending to fewer, verified addresses consistently produces more replies because a healthy sender reputation gets your emails into the primary inbox.
Verification costs $3 per 1,000 emails - so a 10,000-prospect list costs $30 to clean. Every account also includes 100 free verifications per month with no credit card required, so you can test BounceZero on a sample of your Mailshake list before committing.
up to 99.8% accuracy in internal testing on SMTP-verifiable addresses. $3 per 1,000 verifications. Results in seconds. Start with 100 free verifications every month - no credit card required.
Verify your list before loading it into your sending platform
Reply.io sequences fail when email addresses bounce
QuickMail inbox rotation only works when your list is clean
Klenty cadences depend on verified contacts
Pricing, deliverability, and what it cannot do alone
Full review: pricing, inbox rotation, and accuracy gap
Agency cold email - unlimited inboxes + built-in warmup
Continue through related topics
Follow BounceZero