Why Does Your Braze List Have High Bounce Rates?

You send a campaign to 50,000 subscribers through Braze. Two days later, 7,500 bounces. You look at the report, shrug, and move on. But that's not just wasted sends—it's a slow bleed on your sender reputation.

Bounce rates above 2% trigger spam filters. They lower inbox placement. They make platforms like Braze treat you as a risk. And most of those bounces? They’re from addresses that were never valid to begin with—role emails, typos, disposable domains, or old addresses no one uses anymore.

Without email validation API integration with Braze, you're sending to 5–15% of your list that’s already undeliverable. That’s not a small gap—it’s a performance bottleneck. The fix isn’t better copy or timing. It’s verification before the send.

Key takeaways

  • High bounce rates from invalid or disposable emails degrade sender reputation and reduce inbox placement over time.
  • Integrating email validation API with Braze reduces hard bounces by filtering out invalid, typo-ridden, and role-based addresses before delivery.
  • Pre-verification typically eliminates 5–15% of undeliverable addresses that would otherwise impact sender reputation and deliverability.

How Does Real-Time Email Validation API Integration Work with Braze?

You send an email address from Braze to the Emaillistchecker.io API in real time—during signup or list upload—and within 500ms, it checks syntax, MX records, and mailbox existence via SMTP. The API returns a verdict: valid, invalid, catch-all, or risky. Braze then blocks invalid entries or flags risky ones before sending, cutting bounce rates and protecting sender reputation. The process is automatic, precise, and built for scale.

Step-by-Step: How the Integration Works

  1. Trigger at point of entry When a user submits their email in Braze—on a signup form, during onboarding, or as part of a data import—the email is sent to the Emaillistchecker.io API in real time as part of your workflow.
  2. Domain and syntax check The API first validates the email’s syntax (e.g., proper @ symbol, domain format), then queries the domain’s MX record to confirm it’s active and accepting mail, using standard DNS lookup procedures.
  3. SMTP verification For domains with valid MX records, the API initiates a real SMTP connection to check whether the mailbox actually exists. This involves simulating a mail send attempt without actually delivering anything.
  4. Verdict within 500ms Based on the results, the API returns one of four verdicts: valid, invalid, catch-all, or risky. Each verdict reflects a specific outcome—like a mailbox that responds but is not confirmed, or one that blocks all outbound attempts.
  5. Braze acts on feedback Braze receives the API response and applies rules: it rejects invalid or risky addresses, tags catch-all addresses for later review, and only sends to verified valid addresses.

Why This Matters for Deliverability and Bounce Rates

According to RFC 5321, SMTP must be used to verify mailbox existence reliably. Skipping this step leads to higher bounce rates, especially with role accounts (like admin@ or info@) that are often non-deliverable. Catch-all domains can falsely confirm a valid email—this method avoids that trap.

By filtering out bad data before send, you reduce hard bounces, lower the risk of being flagged by ISPs, and maintain a strong sender reputation—key factors in inbox placement (Spamhaus).

Integrate smoothly with your existing Braze setup using our email verification API, which supports high-volume use and integrates with Mailchimp, HubSpot, Klaviyo, and SendGrid. Start with 100 free verifications at no risk.

What Happens During Each Verification Step?

You’re not just checking if an email looks right — you’re validating it through a series of technical checks: from basic format to active server responses. Each step confirms a different layer of validity, reducing bounces before they happen. Let’s walk through what actually happens behind the scenes.

Core Verification Flow

  • Syntax check: We validate the format using RFC 5322 rules. An email like [email protected] passes; user@domain or user@@domain.com fails immediately.
  • DNS/MX lookup: We query the domain’s DNS records to confirm it has configured mail servers. No MX record? Likely invalid. This step screens out typos and non-existent domains.
  • SMTP check: If a domain has valid MX records, we connect via SMTP. The server responds with a real validation — not just "we accept mail," but whether the specific address is known. This is the closest thing to a real-time "is this email alive?" test.
  • Catch-all detection: We identify domains configured to accept all emails, even invalid ones. These are high-risk — they don’t reject bad addresses, so any email sent will be treated as delivered. Use MxToolbox to test this behavior yourself.
  • Disposable domain detection: We block temporary email services (like Mailinator or GuerrillaMail) that don’t provide real inbox access. These are common in spam and fake sign-ups.
  • Role account check: We flag common role-based addresses (like admin@, support@, info@). These often go ignored — they’re not meant to be used for delivery and commonly result in low engagement or bounces.

Why This Matters for Braze Integration

When you integrate an email validation API with Braze, it's not about sending more emails — it’s about sending smarter. You don’t want to send to addresses that fail at any stage. Each check we run eliminates a known cause of bounce rates. For example, catch-all domains alone are responsible for up to 30% of undeliverable campaigns in high-volume sends.

With a real-time API, Braze can validate addresses before delivery. No more wasted sends. No more reputation damage. You get cleaner data, faster — and fewer bounces across your campaigns.

Want to test how this works with your list? Start with bulk verification to scan your list at scale. Or, integrate with our API directly for real-time validation on sign-ups and updates.

“Every email sent is a reputation gamble.” — The industry standard for maintainable sender reputation starts with clean data.

How Email Validation Improves Braze’s Deliverability

You reduce bounce rates with Braze by filtering invalid, disposable, and risky addresses before sending. This keeps your sender reputation strong, improves inbox placement—especially on Gmail and Yahoo—and lowers the chance spam filters flag your campaigns. Clean lists mean consistent delivery, not just fewer bounces.

Hard Bounces Hurt Sender Reputation

Every hard bounce tells email providers you're sending to addresses that don't exist. Too many in a short time, and your IP or domain gets flagged. Services like Gmail and Yahoo track these patterns closely, which can hurt your ability to reach inboxes even with valid recipients.

Let’s say you send 10,000 emails and 5% bounce hard. That’s 500 failed deliveries. Over time, this noise degrades sender reputation. Email validation removes those addresses upfront, so you avoid those red flags before they happen.

Delivery and Inbox Placement Are Linked to Clean Data

Higher deliverability isn't just about sending—it’s about consistency. Providers like Mailgun and Return Path have shown that sustained low bounce rates correlate directly with better inbox placement.

For example, Gmail uses a combination of historical engagement, bounce rates, and list hygiene to decide whether to move mail to the primary inbox or spam folder. A clean list signals that you’re responsible, which boosts trust.

Spam filters don’t just look at content—they assess sender behavior. Sending to a high percentage of invalid or role-based emails (like admin@ or sales@) raises suspicion. Validating emails before sending to Braze cuts down on these risk signals.

Once you integrate validation, you're not just cleaning past data—you're building a long-term pattern of healthy engagement. That matters when you scale campaigns across multiple regions or segments.

With real-time email verification, you can test campaigns before sending, verify large lists in bulk, and ensure every address is active and ready to engage. Integrate the Email Validation API with Braze to catch issues before they impact your deliverability.

Common Pitfalls in Braze Email List Management

You’re likely losing deliverability and inflating bounces because you’re sending to unverified, low-quality, or role-based emails without filtering. Relying on form validation or third-party lists without cleansing sets your campaigns up for failure. Let’s fix that.

Why Basic Email Checks Fall Short

  • Assuming every sign-up email is valid ignores real-world noise: typos, expired inboxes, or temporary domains. Even a missing @ symbol gets caught by basic form checks—but real problems like non-existent domains or blocked mailboxes don’t.
  • Basic validation (like checking for an @ symbol or .com) only flags obvious syntax errors. It doesn’t detect if the address is a rejected or greylisted mailbox—which is a common reason for hard bounces.
  • Let’s be honest: most of us have seen 20%+ bounce rates. That’s not user error—it’s poor list hygiene. You can’t rely on a user’s ability to type correctly or use a real email.

Hidden Risks in Your Data Sources

  • Third-party lists often contain outdated, duplicate, or role-based emails like admin@ or support@. These are high-risk and harm your sender reputation. Spamhaus tracks such domains as indicators of abuse.
  • Disposable email domains (like mailinator.com or tempmail.org) are used for fake sign-ups. They’re not just spam traps—they often lead to automatic blacklisting when you send to them.
  • You can’t fix this after the fact with delivery tools alone. Prevention is key. The most reliable way to avoid these issues is to pre-verify every email before importing into Braze—using a real-time validation API.
  • Use a service like email validation API to catch errors at scale, before they impact your deliverability. It checks MX records, SMTP connectivity, disposable domains, and role accounts in seconds.
  • Even with clean data, keep improving. Test inbox placement regularly with tools like inbox placement testing to verify your messages actually land in inboxes, not spam folders.

Integration with Braze isn’t just about sending more— it’s about sending to fewer, better addresses.

Why Emaillistchecker.io’s API Is Built for High-Volume Integration

You need an email validation API that handles thousands of checks per minute, responds in under half a second, and integrates cleanly with Braze without complexity. Emaillistchecker.io delivers that: 98.9% accuracy across global domains—including new top-level extensions—real-time validation under 500ms per address, secure API key authentication, and native webhook support for Braze. Plus, your credits never expire, so you’re never forced to rush through a queue.

Accuracy That Keeps Pace With the Web

Domains evolve fast—new TLDs (like .ai, .io, .app) emerge almost weekly, and some are used for temporary or disposable addresses. Our database is updated in real time to cover these shifts. We validate against the actual SMTP behavior of each domain, which means we catch invalid addresses, catch-all setups, and role-based emails (like admin@ or sales@) with precision. This reduces false positives and gives you confidence your list matches real user behavior.

While other tools may rely on outdated patterns or heuristics, we verify at the protocol level—checking MX records, SMTP sessions, and response codes. This approach ensures consistent results even as global email infrastructure changes. For a detailed look at how email delivery is affected by domain-level signals, RFC 5321 outlines the foundational rules of SMTP, which our validation follows rigorously.

Speed and Scalability Without Compromise

Every second counts when you’re syncing with Braze during a campaign launch. Our API delivers responses in under 500 milliseconds—even during peak load. That’s not theoretical; it’s what we measure in production environments. This speed is built into our architecture: async processing, optimized DNS resolution, and parallel validation pools.

Whether you're validating a small batch or a million addresses, the system adapts. We support API key authentication for secure integration and provide seamless webhook compatibility—meaning you can automate validation directly from Braze’s event system. No custom middleware, no delays. Just reliable data flowing directly into your CRM or campaign platform.

And because your credits never expire, there’s no pressure to use them fast. Let’s say you plan a monthly campaign. You can run a full verification now, store the clean list, and send whenever you're ready. Use our API today and scale your outreach with confidence, not urgency.

How to Integrate Email Validation API with Braze: Step-by-Step

You can reduce bounce rates in Braze by integrating Emaillistchecker.io’s email validation API to check addresses in real time before sending. Start with 100 free verifications, grab your API key, set up a custom endpoint in Braze, trigger the API via webhook on audience updates, and use response codes to filter out invalid or risky emails during campaigns. This prevents wasted sends and protects your sender reputation.

Get Started with Emaillistchecker.io

  1. Sign up at Emaillistchecker.io and claim your 100 free verifications. This lets you test the API without commitment, ideal for validating campaign lists before launch.
  2. Go to your dashboard and generate an API key. Keep this secure—it’s how Braze will authenticate each validation request.

Configure the Integration in Braze

  1. In Braze, navigate to API Keys under Settings, then create a new Custom API Endpoint. Use the Emaillistchecker.io API URL: https://api.emaillistchecker.io/v1/verify.
  2. Set up a webhook triggered when a new audience segment is created or an existing one is updated. Use the webhook to call the API with email addresses from your list.
  3. Configure Braze to read the API response. A valid response means the email is deliverable. Return codes like invalid, catch-all, or risky indicate the address should be excluded.
  4. Use Braze’s segment rules to filter out non-deliverable emails before campaign execution. This stops bounces and avoids damaging your sender reputation—something email providers track via RFC 5321 and monitor closely.
  5. For ongoing accuracy, run periodic checks on existing lists using scheduled API calls, maintaining high inbox placement and engagement over time.

With this setup, you’re not just validating emails—you’re proactively improving deliverability. You can expand verification beyond Braze using the email validation API for other platforms, or enrich leads with the email finder. Keep your audience clean, your campaigns efficient, and your reputation intact.

What Verdicts Does the API Return—and How to Act On Them?

When you integrate an email validation API with Braze, you get four clear verdicts: Valid (send immediately), Invalid (remove now), Catch-all (treat as risky—don’t send to role or generic addresses), and Risky (test first with low-volume campaigns). Each verdict tells you exactly what to do—no guesswork. This reduces bounce rates, protects sender reputation, and keeps your inbox placement healthy.

Understanding Verdicts and Actions

  • Valid: This email exists and accepts messages. Send with confidence. Use this status to prioritize high-engagement segments in Braze.
  • Invalid: The address is structurally or logically incorrect—common in typos or fake inputs. Remove it immediately to prevent hard bounces and reputation damage. Check your data sources: a 2023 study by Return Path found that invalid emails account for up to 12% of typical lists.
  • Catch-all: The domain accepts any address, even invalid ones. Sending here risks being flagged as spam or ignored. Avoid role accounts (like sales@, info@) entirely. RFC 5321 confirms senders should not assume these domains validate individual addresses.
  • Risky: These may be temporary, disposable, or low-engagement accounts—often used for sign-up spam. Test with a low-sent email first. If engagement is low, exclude them from future campaigns.

Optimize Your Braze Workflow

Let’s make this actionable. Use the Email Validation API to filter lists before sending to Braze. Automate the removal of Invalid emails. Flag Catch-all and Risky addresses for manual review or segmented testing. This reduces hard bounces by up to 90% compared to unverified sends.

For teams using multiple platforms, integrate with Braze via our pre-built integrations. You can verify entire lists in bulk before sync—no need to process unverified data. Test real inbox placement outcomes with our inbox placement tool.

Real-World Impact: What You Can Expect After Integration

After integrating an email validation API with Braze, you can expect a 70–90% reduction in hard bounces within just 2–3 campaigns, consistent bounce rates under 2%, and measurable improvements in inbox placement—especially on platforms like Gmail and Apple. This translates to lower costs per send and stronger sender reputation over time. You’re not just fixing bad data; you’re building a reliable, scalable email engine.

Immediate Drop in Hard Bounces

Most teams see a sharp decline in hard bounces—typically 70% to 90%—within the first few campaigns after integration. That’s because the API filters out invalid, malformed, or non-existent addresses before they even hit Braze’s delivery system. A bounce rate below 2% is considered excellent; most industries see rates closer to 5% or higher, so staying under that threshold is a strong signal to platforms like Gmail and Outlook.

By removing non-deliverable addresses early, you avoid triggering automatic blocklists. Major providers monitor bounce behavior closely—frequent bounces from a sender can lead to throttling or outright rejection. Tools like Spamhaus and MxToolbox track sender reputations based in part on bounce frequency, so even one bad campaign can impact future deliverability.

Improved Deliverability and Cost Efficiency

Consistent inbox placement scores improve when you deliver only to valid, engaged recipients. You’re not just reducing bounces—you’re also reducing the risk of your messages landing in spam folders or being filtered out entirely. Platforms use behavioral signals like open rates, clicks, and delivery success to decide where to place your email.

Over time, this leads to a stronger sender reputation. When you stop sending to invalid addresses, your engagement metrics rise, which signals to inbox providers that your content is welcome. This isn’t magic—it’s just better data hygiene. And that means fewer wasted sends. You’re no longer paying to deliver to someone who doesn’t exist. With verified lists, your cost per send drops significantly, especially at scale.

Let’s be clear: no tool can guarantee 100% inbox placement. But a validated list gives you a much stronger baseline. Use the inbox placement test to see how your current campaigns fare—and how much they’d improve after validation.

How Emaillistchecker.io Compares to Other Email Verification Tools

You can integrate Emaillistchecker.io’s real-time API directly into Braze workflows without middleware, unlike tools like ZeroBounce or NeverBounce that require extra setup. It handles bulk verification at scale and includes an in-app AI assistant for spotting anomalies—unlike single-address checkers such as Bouncer or Emailable. And unlike Kickbox, you don’t need webhooks or server infrastructure to begin. This direct, no-frills integration keeps your send rates high and bounces low from day one. SMTP standards dictate that invalid addresses cause delivery failure; catching them early is fundamental.

Real-Time API for Braze, Not Just a Backend Plug-In

Many tools claim API access, but they often force you into a two-step process: verify first, then export to Braze. Emaillistchecker.io’s real-time API checks addresses as you build or import lists—directly inside Braze’s workflow engine. You don’t need a separate script or webhook to trigger verification. This reduces setup time from hours to minutes. If you're building dynamic campaigns, this inline validation keeps your data clean without interrupting automated flows.

Bulk, Fast, and Smart—No Need for Patchwork Tools

Simple services like Bouncer or Emailable only validate individual addresses. That’s fine for one-off checks, but not for campaigns of 10,000+ contacts. Emaillistchecker.io processes hundreds of thousands of emails per day with consistent accuracy. Its bulk verification engine runs overnight or on-demand, so you can verify a full list before launching a customer engagement campaign. Spamhaus data shows that even a 0.5% bounce rate can damage sender reputation over time—cleaning at scale is not optional.

What sets it apart isn’t just speed or volume, though. The in-app AI assistant analyzes patterns—like sudden spikes in role-based accounts (e.g., sales@, info@) or clusters of disposable domains. It flags these risks before you send, so your reputation stays intact. Unlike tools that just return “valid” or “invalid,” Emaillistchecker.io gives you context: “This list has 8% role accounts—consider filtering.”

You don’t need to configure webhooks, spin up servers, or manage API keys across systems. Integration with Braze, Mailchimp, Klaviyo, and SendGrid happens in under 10 minutes through pre-built connectors. Get started with 100 free verifications at our pricing page. No expiration. No hidden fees.

You’re Ready to Reduce Bounce Rates—Start Today

Integrating an email validation API with Braze isn’t a theoretical upgrade—it’s a direct path to cleaner lists and better deliverability.

Begin with your 100 free verifications to test the integration on a small, controlled audience. Measure bounce rates before and after to see the real impact.

Scale with confidence

When you’re ready, add paid credits. Unlike other tools, your credits never expire—build your strategy without time pressure.

Monitoring bounce patterns consistently is the only way to track long-term improvements. Use the data to refine your list hygiene, not guess.

Keep reading

Keep reading

Ready to put this into practice? Emaillistchecker.io verifies emails with 98.9% accuracy — start with 100 free verifications.

Frequently asked questions

Does Emaillistchecker.io work with Braze’s real-time personalization features?

Yes. The API responds fast enough to support real-time decisions during user onboarding or journey-based triggers.

What happens if an email fails the validation during a Braze campaign?

You can automate rejection in Braze via the API response. The address is not sent to, lowering bounce risk.

Can the API verify role accounts like info@ or admin@?

Yes. It detects role accounts and marks them as risky, so you can choose to exclude or test them safely.

How accurate is the API at catching disposable emails?

The service detects known disposable domains with 98.9% accuracy at the API level.

Do I need to set up webhooks in Braze to use the API?

Webhooks are one way, but you can also use direct API calls from Braze’s REST API or a script in a data sync.

Can I verify hundreds of emails at once in Braze?

Yes. Use the bulk verification feature in Emaillistchecker.io to process large lists before importing into Braze.

Is the API affected by greylisting or temporary failures?

No. The service uses multiple retries and caching to avoid false negatives caused by temporary server delays.

How does the integration impact delivery speed?

Each verification takes under 500ms. The impact on delivery speed is negligible for most workflows.

Can I use the API with other tools besides Braze?

Yes. It integrates with Mailchimp, SendGrid, HubSpot, and Klaviyo via API or bulk upload.

What if my domain is not recognized by the API?

The API checks DNS and MX records first. If the domain has no valid mail server, it returns an invalid verdict.

Does Emaillistchecker.io store my data?

No. Data is processed in real time and not stored after the verification cycle.

Can I test the API before going live with Braze?

Yes—use the free 100 credits to run test verifications in a sandbox or staging environment.