Why Verify Contacts?
Picture this: You’ve just spent weeks building the perfect cold email campaign. The copy is dialed in, your value proposition is crystal clear, and you’re ready to hit send to 5,000 prospects. But here’s what you don’t know—about 1,000 of those email addresses don’t actually exist. Your bounce rate spikes, Gmail flags you as a spammer, and your ESP suspends your account. Three months of work, gone in an afternoon.
This isn’t a hypothetical scenario. It happens every single day to sales teams who skip contact verification.
Unverified contact data creates problems across your entire go-to-market motion. When you send emails to invalid addresses, you’re not just wasting send credits. You’re actively damaging your sender reputation, which affects future deliverability even to valid contacts. Email service providers like Gmail and Outlook track your bounce rates, and high bounces signal that you’re either scraping emails or buying bad lists—neither of which they want to reward with inbox placement.
But email isn’t the only problem. Phone numbers decay even faster than email addresses. People change jobs, switch carriers, and abandon old numbers constantly. When your sales reps spend their day dialing disconnected numbers, you’re burning time and killing morale. Every wrong number is a moment they could have spent talking to an actual decision-maker.
Then there’s the awkwardness factor. Nothing says “I don’t know anything about you” quite like calling someone who left the company two years ago. Or emailing a generic role address that nobody monitors. These mistakes don’t just waste your time—they signal to prospects that you’re running spray-and-pray campaigns instead of doing actual research.
The data backs this up. At any given moment, 15-25% of B2B contact data is invalid. Email addresses get abandoned when people change jobs. Companies get acquired and migrate to new domains. Phone numbers get reassigned. And every month you wait, another 2-3% of your database goes stale.
Email Verification
Email verification is your first line of defense against bad data. Here’s how the process actually works, without the technical jargon.
When you submit an email for verification, the service runs it through a multi-step validation process. First, it checks the basic syntax—is this even formatted like a real email address? You’d be surprised how many lists contain obvious typos like “john@gmai.com” or emails with spaces in them.
Next, the service verifies that the domain actually exists and has valid mail exchange records. This catches emails where someone wrote down “john@companyname.com” but the company actually uses “john@company.io”. It also identifies defunct domains from companies that went out of business or got acquired.
Then comes the interesting part—the mailbox check. The verification service actually pings the mail server to confirm that the specific mailbox exists. It does this without sending an actual email, using SMTP verification commands. This is where you catch most invalid emails—addresses that look legitimate but were never created, or belonged to someone who left the company.
Finally, the service runs quality checks. It identifies disposable email addresses (like those temp email services people use to dodge your newsletter), role-based emails (info@, sales@, support@), and known spam traps—honeypot addresses that exist solely to catch spammers.
The result comes back in one of several categories. “Valid” means the mailbox exists and should be deliverable. “Invalid” means it definitely doesn’t exist—remove these immediately. “Risky” means the email might bounce—these are usually old addresses or ones with deliverability issues. “Catch-all” is a special category where the domain accepts all emails, making it impossible to verify individual mailboxes. And “unknown” means the service couldn’t verify it for technical reasons.
Here’s how to interpret these results in practice. Valid emails are safe to send to. Invalid emails get removed from your list entirely. Risky emails should be excluded from cold campaigns, though you might keep them for warm follow-up if they’ve engaged before. Catch-all emails are tricky—some are legitimate, but you can’t verify individual mailboxes, so test carefully with small batches first. Disposable emails and spam traps should never receive your campaigns.
When to Actually Verify
The timing of verification matters as much as doing it at all. Always verify before cold email campaigns—this is non-negotiable. The cost of verification ($0.005-0.01 per email) is trivial compared to the cost of a suspended ESP account or ruined sender reputation. Also verify immediately after purchasing data or running an enrichment append. Third-party data sources vary wildly in quality, and verification helps you assess what you actually bought.
For ongoing database maintenance, verify your active sales database monthly. These are contacts your team is actively working, and you need them to be accurate. Verify your broader marketing database quarterly—these contacts might not be in active campaigns every month, but you want them clean when you do activate them. And definitely verify before major campaigns or product launches where you’re emailing a large segment of your database.
Choosing Verification Tools
The verification tool landscape is fairly standardized. ZeroBounce and NeverBounce are the market leaders, both offering 99%+ accuracy at around $0.008 per email. They’re fast, reliable, and have good integrations with most CRMs and marketing automation platforms. Bouncer comes in slightly cheaper at $0.006 per email with 98%+ accuracy. Hunter charges a bit more at $0.01 per email but bundles verification with their email finding tools. Debounce is the budget option at $0.005 per email.
Honestly, the differences between these tools are minimal for most use cases. Pick based on price, integration availability, and API documentation quality if you’re building automation.
The Verification Workflow
Here’s what a real verification workflow looks like in practice. You start by exporting your contact list from your CRM or wherever it lives. Make sure to include the email address and at least one identifier like name or company so you can match records back after verification. Export as CSV—every verification tool accepts it.
Upload the file to your verification service or call their API if you’re doing this programmatically. Most services let you select verification depth—basic syntax checks are instant and free, while full mailbox verification takes longer but catches more problems. For cold campaigns, always choose full verification.
The service processes your list and returns results, usually within a few minutes for lists under 10,000 emails. You’ll get a breakdown showing what percentage came back valid, invalid, risky, and unknown. For a healthy list from a good source, you should see 85-95% valid. If you’re seeing lower than 80% valid, that’s a red flag about your data source.
Download the results and filter to valid emails only. Some teams also include risky emails in warm campaigns, but for cold outreach, stick to valid. Import the verified emails back into your system, and critically, tag them as verified and note the verification date. This helps you know when to re-verify later.
Phone Verification
Phone verification is trickier than email verification because there’s less you can programmatically check without actually calling the number. But there are still valuable validation steps you can take.
Basic phone validation starts with format checking. Is this a valid phone number format for its country? Does it have the right number of digits? Is the area code real? This catches obvious data entry errors and fake numbers. You also standardize the format at this stage—adding country codes, removing extensions, and formatting consistently for your dialer.
Line type identification tells you whether a number is mobile, landline, VoIP, or toll-free. This matters because it affects your calling strategy. Mobile numbers are usually better for reaching decision-makers directly. Landlines might route through a receptionist. VoIP numbers might indicate a remote worker or distributed company. Knowing the line type helps you prioritize and adjust your approach.
Connectivity checks actually verify whether the line is active or disconnected. This is the most accurate validation, but it’s also more expensive and has potential compliance implications. Some services can check line status without ringing the phone, while others essentially perform a test dial. Use connectivity checks for high-value campaigns where accurate phone data is critical.
Tools like Twilio Lookup provide line type and carrier information for about $0.005 per lookup. NumVerify offers a free tier for validation plus paid plans for higher volume. Phone Validator specializes in US and Canadian numbers at $0.01 per lookup. Telnyx provides line type and portability data for $0.003 per lookup.
The verification process flows like this: First, run basic validation to remove invalid formats, standardize formatting, and add country codes where missing. Second, perform line type checks to identify mobile versus landline, flag VoIP numbers, and prioritize by type based on your use case. Third, if budget allows and accuracy is critical, run connectivity checks to verify active lines and identify disconnected numbers.
Phone data has unique challenges compared to email. The decay rate is higher—15-20% annually versus 2-3% monthly for email. Numbers get ported between carriers, making carrier lookup less reliable over time. VoIP adoption adds complexity since these numbers behave differently than traditional lines. Do Not Call compliance adds legal risk. And overall, there are simply fewer verification options compared to the mature email verification market.
Company Verification
Beyond individual contact verification, you should also verify company-level data. This prevents embarrassing mistakes like targeting companies that went out of business or pitching services to industries they’re not actually in.
Start with domain verification. Does the company domain actually resolve to a live website? Is it being used for business email, or is it parked? A domain check catches defunct companies and identifies cases where you have the wrong domain on file.
Verify the company name matches what’s on their website and LinkedIn page. Sometimes you have “ABC Corp” in your CRM but they actually go by “ABC Industries” now after a rebrand. Name verification ensures you’re addressing them correctly in outreach.
Cross-check firmographic data like company size, industry, and location. If your enrichment data says they’re a 50-person software company but their LinkedIn shows 500 employees in manufacturing, something’s wrong. Getting these details right isn’t just about data accuracy—it’s about demonstrating that you actually know who you’re talking to.
Use business registries, LinkedIn company pages, and enrichment data cross-checks to verify company information. When you see inconsistencies across sources, dig deeper rather than assuming one source is gospel.
Building a Verification Workflow
The difference between teams with clean data and teams with garbage data usually comes down to having systematic workflows rather than ad-hoc verification.
For pre-campaign verification, establish a hard rule: no campaign launches without verification. Export your target list, run it through email verification, filter down to valid emails only, load the clean list to your campaign tool, and only then launch the campaign. A typical cost example: 5,000 emails at $0.008 each equals $40. That $40 prevents 500-750 bounces and protects your sender reputation. It’s worth it every single time.
For ongoing database maintenance, create a monthly rhythm. Week one, export unverified or old records. Week two, run verification. Week three, update your CRM with the results. Week four, report on quality metrics and trends. This prevents your database from gradually rotting as contacts age.
If you have engineering resources, automate verification for new records. Set up a trigger that queues new contacts for verification within 24 hours of creation. If they come back invalid, flag them for review or automatic removal depending on your confidence in the verification result.
Track verification metrics by data source. Inbound form fills should be 90-95% valid. Enriched data typically runs 85-95% valid. Purchased lists are often 70-85% valid. Old database contacts might only be 60-80% valid. Manual entry is usually 80-90% valid. When you see one source consistently underperforming, you know where to focus improvement efforts.
Verification Metrics That Matter
Good data teams track verification metrics religiously. Your valid rate should be above 90%; below 80% signals a problem with your data source. Bounce rate after verification should stay under 2%; above 5% means your verification isn’t working or you’re not filtering properly. Your overall invalid rate should be under 10%; above 15% suggests you need to clean your database more aggressively. Catch-all rates above 30% can be problematic since you can’t verify individual mailboxes.
Create a monthly verification scorecard. Track how many records you verified, what percentage came back valid versus invalid versus risky, what your post-send bounce rates and spam complaints were, and how these metrics trend over time. Break it down by source to identify which data sources are delivering quality and which ones are wasting your money.
Common Verification Mistakes
The biggest mistake is simply not verifying at all. Teams assume their data is good because it came from a vendor or because it looked clean when they bought it. Verify before every campaign, no assumptions.
The second mistake is verifying once and thinking you’re done. Data decays continuously. Regular re-verification catches contacts as they become invalid over time.
Third, teams often treat catch-all emails the same as verified emails. They’re not. Segment catch-all addresses separately and test carefully with small batches before including them in major campaigns.
Fourth, some teams skip verification to save money, not realizing that bounces cost far more than verification. A ruined sender reputation can take months to rebuild. The cost of verification is trivial compared to the cost of not verifying.
Finally, many teams don’t track verification results to close the feedback loop. Track your bounce rates by segment, by data source, and by campaign. This tells you whether your verification is actually working and helps you identify systematic data quality issues.
Key Takeaways
Contact verification isn’t optional if you care about deliverability and rep productivity. Here’s what you need to remember:
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At any given time, 15-25% of B2B contact data is invalid. This isn’t a data quality problem—it’s the nature of business contacts. People change jobs, companies change domains, and emails get abandoned constantly.
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Verify emails before every cold campaign. The cost is $0.005-0.01 per email. The cost of not verifying is much higher—damaged sender reputation, wasted sends, and campaigns that never reach the inbox.
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Phone numbers decay even faster than emails. If you’re running outbound calling programs, phone verification prevents your reps from wasting time on disconnected numbers.
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Invalid contacts don’t just waste time—they actively hurt your reputation. High bounce rates trigger spam filters. Wrong person outreach makes you look lazy. These mistakes compound over time.
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The cost of verification is trivial compared to the cost of bad data. A $40 verification bill that prevents 750 bounces and protects your sender reputation is one of the best investments you can make in your outreach program.
The teams winning at outbound aren’t using better copywriting or more sophisticated sequencing. They’re winning because they consistently reach actual human beings with working email addresses and phone numbers. Verification is how you make that happen.
Need Help With Data Verification?
We’ve verified millions of contacts and built verification workflows for sales teams across every industry. If you want clean, reliable data without the manual work, book a call with our team to discuss how we can help.