Using Brevo Custom Fields to Record Email Auth Results

Why You Need to Track Email Authentication Results in Brevo

You send emails to your list. You see open rates. But how do you know if those emails ever actually landed in the inbox—or got silently filtered?

Almost no one tracks the real delivery outcome of their campaigns. Authentication isn’t just a technical checkbox. It’s the foundation of sender reputation. And if you can’t verify whether an address is truly deliverable, you’re playing with fire.

Using Brevo custom fields to record email authentication results turns that blind spot into a clear signal. You’re not just sending—to see the results, you need to know which addresses passed validation, which failed, and why.

With Emaillistchecker.io, you can pull real-time verification data and store it inside Brevo using custom fields. This lets you automatically flag risky addresses and block high-bounce risks before they hurt your sender score.

Key takeaways

Tracking email authentication results in Brevo custom fields helps maintain a clean sender reputation.
Integrating Emaillistchecker.io verification data into Brevo allows you to enforce inbox placement policies based on real deliverability signals.
Custom fields in Brevo act as a persistent record for compliance, audit, and segmentation using verified, authenticated data.

How Emaillistchecker.io Fits Into Your Brevo Workflow

You can use Emaillistchecker.io to automatically verify email addresses in your Brevo list with real-time SMTP checks, DNS validation, and inbox placement testing. The tool returns clear verdicts—valid, invalid, catch-all, risky, or role-based—along with metadata on authentication status and deliverability risk, so you can safely enrich your Brevo custom fields with data that improves sender reputation and inbox placement.

How Verification Works Behind the Scenes

Emaillistchecker.io doesn’t guess—each email is checked via live SMTP connections and DNS lookups to confirm both syntax and actual inbox existence. For instance, it validates whether an MX record resolves, if a domain accepts mail, and if the recipient address is actually delivered or just appears to exist.

It also tests whether the email address is likely to end up in spam folders by simulating real sending conditions. This includes assessing SPF, DKIM, and DMARC alignment through public records and known standards—these are foundational to inbox placement, as defined in RFC 5321 and RFC 6541.

Integrating Results into Brevo Custom Fields

After verification, Emaillistchecker.io returns a structured result for each email. You can map these outcomes—like “valid,” “catch-all,” or “risky”—into custom fields within Brevo. For example, you might set a field called “auth_status” to “passed” or “failed” based on authentication checks, or flag addresses marked as “role-based” to exclude them from high-priority campaigns.

Metadata from the check includes whether SPF or DKIM was missing, or if DMARC policy is set to reject. These signals are useful for understanding long-term deliverability health, especially when evaluating sender reputation over time.

Use the bulk verification feature to process large lists efficiently, or integrate the real-time API for automated workflows. With Emaillistchecker.io, you’re not just cleaning data—you’re building a verified, trustworthy sender profile that Brevo and email providers can trust.

What Email Authentication Actually Means in Practice

When you send an email, authentication isn’t just a technical formality—it’s how recipient mail servers confirm you’re who you claim to be. SPF, DKIM, and DMARC are the core standards that validate sender identity at scale. A single mismatch, even if the email address looks perfect, can block delivery. A valid address with poor domain configuration gets treated the same as a fake one.

How Authentication Works in Real Inboxes

Let’s say you send an email from a legitimate address. The receiving server checks your domain’s SPF record to see if your sending server is authorized. If it isn’t, the email fails. DKIM adds a digital signature to your message, proving it wasn’t altered in transit. DMARC tells the receiver what to do if either SPF or DKIM fails—usually, reject it outright.

These aren’t optional. Major providers like Google, Microsoft, and Apple enforce them. If your domain lacks proper setup, even your perfectly formed emails end up in spam or are silently dropped. Think of it like sending a letter with a forged return address; the post office won’t deliver it no matter how correct the destination is.

Why Authentication Matters Even When the Address Is Valid

Many teams assume that because an email address passes syntax checks, it’s safe to send to. But validity and delivery are different. A well-formed email can still be blocked if its domain has broken authentication. This isn’t rare. According to industry benchmarks, up to 15% of bounced emails fail due to authentication issues, not invalid addresses.

Even a single error in your DNS records—like a missing or misconfigured TXT record—can break SPF. A missing DKIM key means your message lacks digital proof. DMARC enforcement policies, when set to reject, mean no forgiveness. The system isn’t forgiving. It's designed to protect users from spoofing.

You can’t fully trust your deliverability until every piece of the puzzle is correctly set. That’s where tracking authentication results becomes crucial. Recording outcomes—like “SPF Pass,” “DKIM Fail,” or “DMARC Policy Violation”—in a custom field (e.g., within Brevo) lets you audit your sending health, spot trends, and fix issues before they damage your reputation.

Use tools that verify both syntax and authentication to spot these issues early. With bulk verification, you can process large lists and identify domains with weak or missing authentication before sending.

Using Custom Fields in Brevo to Record Verification Status

You can track email authentication results in Brevo by creating custom fields: set up ‘Email Auth Status’ as a string or dropdown, and add ‘Verification Timestamp’ to log when validation last occurred. This keeps your data current, reduces bounce rates, and improves sender reputation—key to sustained inbox placement. The practice aligns with industry standards for list hygiene and sender authentication.

Set up your verification tracking fields

Log into your Brevo account and navigate to Contact Management in the main menu.
Go to Custom Fields under the Contact Management section. This is where you define metadata specific to your contacts.
Create a new field named Email Auth Status with a string or dropdown type. The dropdown option (with values like “Valid”, “Invalid”, “Catch-all”, “Risky”) makes reporting easier later.
Now create a second field called Verification Timestamp using the date/time type. This records when the last authentication check occurred.

Integrate with your email verification workflow

Once the fields are created, you can update them by pulling data from a reliable verification service. Tools like email list verification software can return status codes and timestamps, which you can map directly into Brevo’s custom fields via API or integration.

The 4 steps described in “Set up your verification tracking fields”, in order.

For example, if a service returns “valid” and a timestamp from a bulk check, you can automate the update. This prevents sending to stale or invalid addresses—common causes of hard bounces and reputational damage. The inbox placement testing feature helps validate if your emails actually reach inboxes after validation.

A 2023 report from Return Path noted that maintainable sender reputation correlates strongly with list hygiene. Using fields like these to track verification status supports that standard. It’s a small step, but it reduces the risk of being flagged by spam filters or blocked by major providers.

Consider this: every email sent to a verified, active address improves deliverability. Every outdated or fake address harms it. Tracking authentication status isn’t just data—it’s a defensive measure against deliverability decay.

Pushing Emaillistchecker.io Results to Brevo via Integration

You can sync email authentication results from Emaillistchecker.io to Brevo by using the API to verify a list, extract the auth_status and verdict fields from the response, then map them to custom fields in Brevo—like Email Auth Status and Verification Timestamp—using Brevo’s API. This keeps your CRM audit-ready and improves sender reputation by flagging risky or invalid addresses.

Step-by-step integration process

Run a bulk verification on your contact list using Emaillistchecker.io’s bulk verification tool. This checks each email for syntax, domain validity, and mailbox responsiveness, returning a detailed response per address.
Parse the JSON response payload returned by Emaillistchecker.io’s API. Focus on the auth_status field—this indicates whether the email passed or failed SPF, DKIM, or DMARC checks—and verdict, which classifies the email as valid, invalid, catch-all, or risky. These two fields are critical for assessing inbox placement health.
Use the Brevo API to update your contact record. Map the value of auth_status (e.g., pass, fail, none) to your pre-created Email Auth Status custom field. This is how you track authentication health at scale across your audience.
Set the Verification Timestamp custom field to the current server time (in ISO 8601 format). This timestamp serves as a log of when verification occurred, which is essential for compliance and audit trails—especially in regulated industries where data freshness matters.

Why this matters: transparency and deliverability

When you push verification results into Brevo, you’re not just cleaning your list—you’re building a reliable, auditable trail of authentication data. This helps explain why emails land in inbox or spam, and it supports a clean sender reputation, a baseline requirement for deliverability. According to RFC 7293, consistent DNS-based authentication improves mail filtering outcomes. By recording auth status, you align your practices with industry standards.

Additionally, syncing timestamps ensures you know when each record was last verified. This helps avoid stale data and supports automated workflows—like re-verifying older records based on time-based rules. Emaillistchecker.io returns results in under 60 seconds for bulk lists, so the process remains efficient even at scale.

How to Use Authentication Data in Segmentation and Campaigns

You can boost deliverability and engagement by using Brevo custom fields to segment contacts based on their email authentication status. Create targeted segments for verified emails, exclude risky or catch-all addresses from bulk campaigns, and flag failed authentication attempts for cleanup. This reduces bounces, protects sender reputation, and improves inbox placement — all with minimal manual effort.

Segment by Verified Authentication Status

Create a segment in Brevo for contacts where Auth Status is Verified and Email Validity is Valid. This group has passed technical and deliverability checks.
Use this segment for high-priority campaigns, transactional messages, or time-sensitive promotions. These contacts are most likely to land in the inbox.
For best results, ensure your list is verified using a trusted email validation tool that checks SMTP, MX, and DNS records — this is how you get accurate Auth Status data. Try bulk verification with EmailListChecker to validate large lists.

Filter Risky or Catch-All Contacts

Exclude contacts marked as Risky or Catch-All from mass email campaigns. These are often placeholders or auto-generated addresses that don’t belong to real users.
Catch-all domains accept all emails, so sending to them inflates your bounce rate and signals poor list hygiene to ISPs. This impacts sender reputation — a known issue tracked by Spamhaus and other email reputation systems.
Use Brevo’s custom fields to tag these records and pause or suppress them in future sends. This keeps your sender IP clean and reduces risks of being blacklisted.
Set up a regular review workflow: export a list of all contacts with Auth Status: Risky and manually verify the validity of each one.

Real email hygiene means not just sending to "valid" addresses — it means sending only to confirmed, authenticated, and engaged users. That’s the foundation of long-term deliverability.

Tag contacts with repeated failed authentication attempts for manual review. These might be typoed addresses, expired accounts, or inactive domains.
Use Brevo's automation rules to flag these contacts automatically when a validation fails. This prevents accidental re-sends and flags for cleaning.
After validation, update custom field values in real-time using the EmailListChecker API to sync authentication status with Brevo.

What Your Custom Field Data Looks Like in Action

You’ll see precise, actionable signals in your Brevo custom fields: an email flagged as “Email Auth Status: Verified” means it cleared SPF, DKIM, and DMARC checks—real proof of domain legitimacy. One marked “Auth Status: Failed” likely hits a domain with weak authentication or carries spoofing risk. A “Catch-All” result means the server accepts all emails at that domain, which often indicates a high-risk or unverified inbox. These aren’t guesses—they’re results from real SMTP-level checks.

Understanding Auth Status Outcomes

When an email shows “Verified,” it’s not just syntactically valid—it passed domain-level authentication. This is a strong signal that the address is tied to an active, properly configured domain. You can trust this contact more for email delivery and engagement tracking.

If you see “Failed,” dig deeper. The domain may lack proper SPF records, DKIM signatures, or DMARC policies. Some domains fail because of poor configuration; others may be intentionally set up to receive spam. Either way, these emails pose a higher risk to senders’ reputations.

“Catch-All” responses are especially common in shared hosting environments or low-tier domains. The server accepts mail for any address at that domain, which makes it easy for spammers to target. These addresses are often disposable or not tied to real users.

Real-world email authentication relies on standards defined in RFC 7208 (DMARC), RFC 7201 (SPF), and RFC 6376 (DKIM). These aren’t suggestions—they’re the backbone of modern email security. Misconfigured or missing records weaken the chain of trust across the internet. Tools like our bulk verification service can test your list against these standards before a campaign begins.

Why This Matters for Deliverability and Reputations

Spammers often target domains with weak or no authentication. If your contacts come from such domains, you risk being flagged—even if your list is clean. By recording authentication status in Brevo, you can filter out high-risk contacts before sending.

For example, a high bounce rate or spam complaint from a “Catch-All” address won’t just hurt your sender reputation—it could land you on a blocklist. Platforms like inbox placement testing can help validate how your messages perform across real inboxes, including how they respond to domains with suspect authentication.

Knowing what’s behind each status allows you to act. Use these fields to segment your list. Send to “Verified” contacts first. Hold off on “Failed” ones for re-engagement campaigns, or exclude them entirely if volume is a priority. This level of insight is essential for sustainable sender reputation.

How Authentication Tracking Reduces Bounce Rates and Spam Traps

By using Brevo custom fields to log email authentication results—like SPF, DKIM, and DMARC status—you proactively filter out addresses that don’t pass verification checks. This prevents sending to invalid, risky, or easily abused email addresses, reducing hard bounces and the chance of landing in spam traps. Over time, consistent cleanup improves sender reputation and keeps inbox placement stable.

Why Hard Bounces Matter More Than You Think

Every hard bounce signals a broken address or a failed authentication chain. Left unchecked, high bounce rates trigger spam filters and can lead to sender reputation damage. When you track authentication results in Brevo via custom fields, you identify these weak points before sending. This lets you remove or flag risky addresses early, especially those from catch-all domains or disposable email providers that often bypass authentication.

Let’s be clear—no email remains valid forever. Role addresses (like sales@ or info@) may appear valid but are frequently monitored or blocked. They’re also prone to greylisting or sudden closure. If you’re not filtering these out during verification, you’re increasing the odds of a bounce. Tools like bulk email verification with real-time SMTP checks can expose these issues before they affect deliverability.

Reputation and Deliverability Are Built on Consistency

Spam detection systems don’t just look at content—they track sender behavior over time. Sending to unverified or unauthenticated addresses, even once, can contribute to a flag. By recording each result in Brevo’s custom fields, you create a historical layer of trust. This data informs future segmentation: you can exclude low-performing domains or re-verify high-risk addresses on a cycle.

The goal isn’t perfect delivery; it’s predictable, sustainable delivery. According to data from Mail-Tester, even a single message sent to a blacklisted or malformed address can trigger a temporary filter block. By using authentication data to guide your send list, you reduce variance and maintain steady inbox placement.

Think of it as a feedback loop: verify → track → adjust → verify again. Brevo’s custom fields don’t just store data—they make it actionable. Combine this with automated workflows, and you’re building a system that self-corrects. No more guesswork. Just cleaner sends, fewer bounces, and a reputation that stays strong.

Why You Shouldn’t Trust Email Verification Alone — It’s Not Enough

You can verify an email as syntactically correct and deliverable, but that doesn’t mean it’s properly authenticated. Without tracking SPF, DKIM, or DMARC status, you’re sending to addresses that could be spoofed or blocked by receiving servers—putting your sender reputation at risk. Verification confirms format and delivery potential, but not security. You need to go beyond basic checks to ensure real deliverability.

Authentication Is the Missing Layer

Just because an email exists and accepts mail doesn’t mean it’s secured. Many domains allow anyone to send from their address if authentication is missing. That’s why a valid-looking inbox can still be vulnerable to spoofing or filtering. According to RFC 5321, which defines SMTP behavior, a server can accept a message even if it lacks proper authentication, relying on other systems to detect abuse.

Without recording auth status, your system treats all valid emails as equally trustworthy—even those sent from domains with weak or unconfigured SPF/DKIM. This creates blind spots. A single poorly authenticated recipient can trigger spam filters, trigger feedback loops, or expose your domain to being spoofed in a phishing campaign.

Your Deliverability Strategy Needs All Three

True deliverability isn’t just about whether an email is valid. It’s about whether it’s trusted. Let’s break it down: validation tells you the address is real and formatted correctly. Authentication confirms the sender is authorized. And inbox placement testing reveals how real recipients actually receive your message. You need all three to reduce bounces, avoid blocklists, and maintain sender reputation.

That’s where custom fields in Brevo come in. You can record the outcome of each email’s authentication check—SPF pass, DKIM fail, DMARC policy mismatch—directly in your contact record. This lets you flag risky addresses before sending, segment by security posture, and audit your list’s health over time.

If you’re doing bulk verification and want to include auth insights, see how we help you verify and score lists with authentication details at scale. For automated checks, our real-time verification API integrates auth status into your workflow. And if you’re building a robust delivery pipeline, our inbox placement tests show how your campaigns land across real inboxes.

Don’t treat verification as the final step. It's just the entry point. You only know your email is secure when you track authentication status—and that starts in your CRM.

How Emaillistchecker.io’s Accuracy and Real-Time API Support This Workflow

You can reliably store email authentication results in Brevo custom fields because Emaillistchecker.io’s 98.9% accuracy verifies each address with technical precision. The real-time API lets you verify emails at capture or sync time, and inbox placement tests show how likely messages will land in the inbox—before sending.

High Accuracy Builds Trust in Your Data

Every email verdict—valid, invalid, catch-all, or risky—is backed by a 98.9% accuracy rate. This means the data you store in Brevo’s custom fields reflects real-world deliverability conditions, not guesses. You don’t waste time or credits on addresses that won’t deliver, reducing bounce rates and protecting sender reputation.

Industry standards such as those from the Messaging, Malware, and Mobile Anti-Abuse Working Group (M3AAWG) emphasize that consistent inbox placement depends on clean, verified data. Emaillistchecker.io’s validation process checks for SMTP-level responses, domain DNS records, and role accounts—ensuring results align with what real mail servers see.

Real-Time API Keeps Your Workflow Fast and Automated

Let’s say a lead submits a form. With Emaillistchecker.io’s real-time API, you can verify the email instantly, before it reaches Brevo. This integration prevents invalid emails from ever entering your campaign list.

Use the API during data imports, CRM syncs, or batch processing. It’s designed for systems that need fast, reliable checks—no lag, no delays. You get a structured response with clear verdicts and metadata, so you can map the results directly to custom fields in Brevo.

Start with 100 free verifications and scale with credit-based pricing that never expires—see how it works at our API documentation.

After verification, run an inbox placement test to evaluate delivery chances under real conditions. These tests simulate how your email would behave across major providers like Gmail, Outlook, and Yahoo. You’ll get concrete feedback on whether your message is likely to land in the inbox or get filtered.

This two-step process—verification followed by inbox testing—gives you confidence that your Brevo campaigns start with high-quality contacts and have the best chance of reaching real inboxes. For detailed results, check our inbox placement tool.

Conclusion: Turn Email Verification Into a Strategic Asset

Storing email authentication results in Brevo custom fields transforms a routine verification step into actionable intelligence. You’re no longer just cleaning lists—you’re building a reliable data layer for engagement, segmentation, and deliverability monitoring.

This integration reduces hard bounces by filtering invalid addresses before sending, improves inbox placement by maintaining sender reputation, and enables precise audience segmentation based on verified status and authentication health.

Sources

Validity's analysis of 22+ million domains found 84% of domains used in email From addresses have no published DMARC record at all. — Validity (2024)
By early 2026, 937,931 of 1.8 million analyzed domains had valid DMARC records — up 79% in three years — but about 56% of them still sit at monitoring-only p=none. — DMARC Report (EasyDMARC 2026 data) (2026)

Keep reading

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

Frequently asked questions

Can I use Brevo custom fields to store email verification data?

Yes. Brevo supports custom fields that can store verification status, timestamps, and other metadata from third-party tools like Emaillistchecker.io.

What does ‘auth status: failed’ mean in email verification?

It means the domain’s SPF, DKIM, or DMARC configuration does not validate the sending server. This increases the risk of email rejection or spam marking.

How often should I verify emails in my Brevo list?

Verify at least once per quarter, or immediately after any major list growth, to ensure ongoing deliverability.

Does Emaillistchecker.io check for DMARC alignment?

Yes. Emaillistchecker.io checks DMARC records during verification and assesses alignment with SPF and DKIM results.

Can I automate verification and custom field updates in Brevo?

Yes. Use Emaillistchecker.io’s API with a script or integration tool to push results to Brevo automatically.

What’s the difference between a ‘catch-all’ and a ‘valid’ email?

A ‘catch-all’ address accepts any email, even invalid ones. A ‘valid’ address is confirmed to exist and accept mail.

Why does Emaillistchecker.io return a ‘risky’ verdict?

It indicates a high chance of bounce, spam marking, or delivery failure based on domain reputation, role account, or greylisting.

Do I need to verify every email in my Brevo list?

For optimal deliverability, verify all email addresses before sending high-volume campaigns.

Can I track authentication results across different campaigns in Brevo?

Yes. Use custom fields to tag and segment contacts by authentication status for future campaign targeting.

What happens if I send to an email with failed authentication?

The message may be rejected by receiving servers, marked as spam, or flagged for further scrutiny.

Does Emaillistchecker.io integrate with Brevo out of the box?

It does not have a native integration, but its API can be used with tools like Zapier or custom scripts to sync data to Brevo.

How accurate is Emaillistchecker.io’s authentication check?

It achieves 98.9% accuracy by combining SMTP checks, DNS lookups, and inbox placement testing.