Why a Sender Score below 70 means your emails aren't landing

You send emails. They don’t land. You don’t get bounces—but you don’t get replies either. Your open rates are flat. The issue isn’t your message. It’s your Sender Score.

A Score below 70 means major ISPs like Gmail, Yahoo, and Outlook don’t trust you. Not because your content is spam—but because your sending behavior raises red flags. One high bounce rate. One spam complaint. That’s enough to push you into the danger zone.

Think of Sender Score as a credit report for your domain. Low scores don’t mean you’re blocked—they mean you’re under scrutiny. Your emails get quarantined, delayed, or quietly buried.

Key takeaways

  • Sender Score below 70 signals poor reputation with major ISPs, increasing inbox placement risk.
  • Even one spam complaint or high bounce rate can push your score into the danger zone.
  • Low score doesn’t mean spam—just reduced deliverability due to sender reputation issues.

What really determines your Sender Score? The top 5 factors

Sender Score below 70? Focus first on hard bounces, spam complaints, and email hygiene. High bounce rates (>5%), frequent complaints, and sending to invalid or role-based addresses are the fastest ways to damage your reputation. Consistent volume and proper authentication (SPF, DKIM, DMARC) are equally critical. Fixing these five areas gives you the clearest path back to a healthy score.

Check your sending habits and list quality

  • Check for sudden volume spikes. Email providers track sending patterns. A 10x increase in one day raises red flags — even if your content is clean.
  • High hard bounce rates (>5%) signal poor list hygiene. You’re likely sending to outdated or fake addresses. This directly lowers your Sender Score.
  • One spam complaint from a major provider (like Gmail or Outlook) can trigger a reputation hit lasting weeks. Monitor complaints closely — one is too many.
  • Remove disposable, role-based, and catch-all addresses from your lists. These are high-risk and commonly abused by spammers.
  • Use real-time verification before your sends. Tools like MailTester’s Email Verification API can catch invalid addresses before they cause bounce issues.

Verify your email authentication setup

  • Missing or misconfigured SPF, DKIM, or DMARC reduces trust. Without them, most major providers treat your emails as suspicious.
  • SPF must list only your sending domains. Overly broad policies can cause authentication failures.
  • DKIM signatures must be valid and not expired. Use a tool like MailTester’s Inbox Placement Tester to check how your messages appear on real inboxes.
  • DMARC policies enforce your authenticity rules. Set a policy (p=none, p=quarantine, p=reject), and monitor reports to catch issues early.
  • Keep your DNS records updated. Changes to your servers or providers require updates to SPF and DKIM — a lapse here is one of the most common mistakes.
Authentication isn’t a checkbox. It’s your digital fingerprint. If it doesn’t match, your email won’t get past the gate.

These five factors — volume consistency, bounce rate, complaints, list hygiene, and authentication — are what ISPs use to judge your trustworthiness. Fixing them isn’t a one-time task. It’s ongoing hygiene. Use MailTester to verify your list before every send. You’ll catch problems early, reduce bounces, and build a long-term reputation that delivers.

Check your Sender Score before you fix anything

Before you adjust anything, verify your current Sender Score using a trusted tool like SenderScore.org or MxToolbox. A score below 70 isn’t just a number—it’s a red flag that you’re on a path to inbox rejection. Don’t guess at problems. Use the score as your starting point for a targeted fix, not a panic response.

Diagnose with data, not assumptions

  1. Check your Sender Score today. Visit SenderScore.org or MxToolbox and enter your sending domain or IP. These tools tap into real-time reputation data used by mailbox providers, giving you a clear, third-party view of how you're seen.
  2. Confirm the score is a trend, not a blip. A single dip below 70 might be due to temporary issues—like a spike in complaints or a misconfigured sending infrastructure. Check scores over multiple days. Sustained low scores signal deeper problems.
  3. Map your domain and IP reputation. SenderScore uses a combination of spam traps, feedback loops, and aggregate data from major ISPs. If your score is low, it means one or more of those signals are active against you—often due to poor list hygiene or unverified sending practices.
  4. Correlate with real deliverability results. Use tools like MailTester’s inbox placement tester to simulate how your emails land in real inboxes. A poor Sender Score paired with high bounce rates or inbox placement drops confirms systemic issues in your sending practice.
  5. Fix based on the root cause, not symptoms. If your score is low, don’t just tweak SPF. First, audit your email list. Then verify sender reputation with a tool like MailTester’s bulk verification. Remove invalid or risky addresses before sending.

Track progress, don’t react

Sender Score improves slowly. It’s not a magic switch. Once you’ve cleaned your list and validated addresses using MailTester’s API or integrations, give it time—days to weeks—to reflect changes in the ecosystem.

Use consistent monitoring: check your score weekly. If it stabilizes above 70, you’re on track. If it drops again, repeat the diagnosis. Reputation isn’t built in a day, but it is rebuilt—with clarity and care.

Let’s not fix what we haven’t measured. Your Sender Score is not just a number—it’s your inbox access pass. Treat it as such.

Start with the biggest reputation risk: your email list

If your Sender Score is below 70, the most immediate fix is cleaning your email list. High bounce rates and invalid addresses signal poor list hygiene to email providers, directly dragging down your reputation. Even a 5% invalid rate is enough to trigger filters at Gmail, Apple, and Outlook. Start by scrubbing your list with a tool like MailTester to remove dead, catch-all, and disposable emails before sending.

Why bounce rates kill Sender Score

Bounces are a red flag. Every non-delivery, whether hard or soft, gets tracked by major email providers. High bounce rates — especially hard bounces — mean you're sending to addresses that don’t exist, or are temporarily unreachable. After just a few sends with high bounce rates, providers may throttle or block your domain entirely.

Industry standards from sources like Spamhaus and Return Path (now part of Google's postmaster tools) consistently point to a threshold of 5% invalid deliverables as the tipping point for reputation damage. Beyond that, even reputable senders get treated with suspicion.

What to look for — and how to fix it

Not all bounces are equal. Invalid addresses (like non-existent emails) are a hard signal. Catch-all addresses (which accept any email) inflate your bounce rate without giving you real engagement. Disposable domains (like temporary emails from Mailinator or TempMail) never open or respond — and often indicate spam traps or fake signups.

Let’s be honest: if you’re not verifying your list, you’re likely sending to hundreds of dead or fake addresses. That’s not just wasteful — it’s dangerous. Use a bulk verification tool like MailTester’s list checker to identify and remove these risks before they harm your sender reputation.

For ongoing hygiene, integrate MailTester’s real-time API into your signup or CRM workflow. This stops bad addresses at the door and keeps your list clean long-term. No more guessing, no more wasted sends. Just verification built into your process.

Verify your list with MailTester: accuracy, speed, and real-time feedback

If your Sender Score is below 70, the first fix is cleaning your email list. Invalid, catch-all, and risky addresses damage sender reputation and hurt deliverability. MailTester’s bulk verification identifies these in minutes with 98.9% accuracy, helping you eliminate the biggest contributors to poor scores — all without needing to send a single test email. Start by testing 100 addresses free.

What you get when you verify your list

  • Identify invalid emails with real-time diagnostics — no more wasted sends on addresses that bounce permanently.
  • Spot catch-all domains that accept any address but rarely deliver, reducing your bounce rate and protecting your sender reputation.
  • Flag risky addresses (like role-based or disposable inboxes) that may lead to spam complaints or low engagement, both red flags for providers like Gmail or Outlook.
  • Verify up to 100 emails at no cost — no credit card required. Test how your list performs before scaling.
  • Use the real-time verification API to validate every new sign-up before it enters your CRM or email service.

Integrate, test, deliver with confidence

Once your list is clean, integrate MailTester with your stack to maintain quality over time. The pre-built connectors for Mailchimp, HubSpot, and SendGrid plug directly into your workflow, verifying every new subscriber before a single campaign goes out.

For full inbox placement testing, run a real inbox test against real inboxes to check how your message performs under actual delivery conditions — a step beyond basic validation.

Delivery starts with a clean list. High bounce rates and poor engagement drag down Sender Score. By catching invalid, risky, or unengaged addresses early, you reduce harm to your reputation across major providers. The industry-standard approach to sender reputation isn’t just sending more mail — it’s sending smarter.

When your sending practices align with email authentication best practices (SPF, DKIM, DMARC), and your list quality is verified at scale, you’re closer to a stable, long-term Sender Score. You’re not guessing. You’re checking. And you’re doing it fast.

What each verification verdict means in practice

You’re not just checking if an email exists—you’re assessing deliverability risk. A Valid address is safe to send to. Invalid means it should be removed now. Catch-all suggests the domain accepts any address, which often means disposable or low-quality inboxes. Risky means the address is likely to bounce, land in spam, or be delayed—use extreme caution. These verdicts reflect real-world delivery outcomes, not just syntax checks.

Verification verdicts in real-world terms

Each verdict tells you more than just “valid” or “invalid.” Here’s what they actually mean during a real email send:

Verdict What it means Next step Common signs
Valid Address exists and accepts mail. No syntax or server errors. Likely to be delivered to the inbox. Safe to include in your next campaign. Found at the domain’s MX level. Responds correctly to SMTP handshake.
Invalid Address never existed or is permanently undeliverable. Often a typo, old account, or banned domain. Remove immediately. Sending to invalid addresses harms sender reputation. Returned as 5xx error (e.g., 550 No such user). Not reactivatable.
Catch-all Domain accepts mail for any address, even fake ones. Common on free or disposable domains. High risk. Avoid sending to these addresses unless strictly necessary. Mail servers that allow all emails regardless of recipient. Often linked to shared hosting or temporary domains.
Risky Address is technically valid but likely to be blocked, delayed, or marked as spam. Often due to reputation or greylisting. Use caution—especially in cold outreach. Test with inbox placement tools. See delays via SMTP, greylisting, or spam filtering. Common in corporate or heavily monitored domains.

The distinction between Valid and Risky matters. A Valid address may still end up in spam if the recipient’s inbox rules are strict. A Risky address may bounce later or be flagged by the receiving server. The SMTP standard defines how servers respond, but real-world behavior (like greylisting) adds layers of complexity you can’t see in a syntax check alone.

If you're trying to improve your Sender Score below 70, start here. Remove all Invalid addresses. Avoid Catch-all domains. Test Risky ones with inbox placement testing. A clean list is the foundation of healthy deliverability. You can check hundreds of emails at once with our bulk verification tool, or integrate verification in real time with our API.

Clean your list before sending: the only way to rebuild trust

If your Sender Score is below 70, the first fix isn’t tweaking your subject line—it’s pruning your list. Invalid addresses, catch-all domains, and inactive users poison sender reputation. Remove them now. Your domain’s trust starts with a clean slate.

Start with invalid and risky emails

  • Run your entire list through a real-time verification service to flag every invalid address. These bounce and hurt deliverability.
  • Eliminate risky addresses—those with known spam patterns, disposable domains, or high abuse rates. Services like MailTester catch them with a 98.9% accuracy rate. Bulk verify your list.
  • Never send to addresses that return a hard bounce. They signal poor list hygiene to ISPs.

Handle catch-alls and inactivity with care

  • Unless you're testing deliverability, exclude catch-all domains. They mask invalid addresses and inflate your bounce rate. Test deliverability with MailTester’s inbox placement tool to confirm.
  • Segment out users who haven’t opened an email in 12 months. They’re dead weight—high spam risk, low engagement.
  • Send a re-permission email to inactive users. Ask permission to stay in touch. If they don’t respond, remove them. This preserves reputation, and respects user choice.
  • Don’t send to inactive users unsolicited. Even “no harm” bulk sends count as spam signals. Spamhaus and RFC 6655 confirm that unengaged recipients degrade sender reputation.
Trust isn’t rebuilt by sending more. It’s rebuilt by sending only to those who want to receive.

You don’t need to perfect everything at once. Just start with the biggest risks. Clean lists cut bounces, lower spam complaints, and improve inbox placement. Use MailTester’s API for real-time checks, or link directly to your CRM with our integrations. Every dollar saved on failed sends is one more you can spend on real engagement.

Fix authentication: SPF, DKIM, DMARC—non-negotiable foundation

If your Sender Score is below 70, start with authentication. Misconfigured or missing SPF, DKIM, or DMARC settings are among the top reasons emails get rejected or marked as spam. Correcting these fundamentals often lifts scores fast, even if other issues linger. You can’t build trust without proof of legitimacy.

SPF: Authorize your sending servers

SPF tells receiving mail servers which IP addresses are allowed to send emails on your domain’s behalf. Without it, your emails can be flagged or blocked as spoofed. If you use multiple platforms—like your own server, Gmail, and a marketing tool—SPF must include all of them. Overly restrictive policies can accidentally block your own legitimate mail.

DKIM: Sign your messages cryptographically

DKIM uses a digital signature attached to each email. It proves the message wasn’t altered in transit and comes from your domain. Every outgoing message should be signed, and the public key must be published in DNS. Even a single missing signature can trigger filtering, especially for high-volume senders.

DMARC: Set rules for failed authentication

DMARC tells receiving servers what to do when SPF or DKIM fails. It's the enforcement layer: you can set it to monitor (none), quarantine (reject, but allow delivery), or reject outright. A policy of none or misconfigured reject is a common cause of delivery issues—even if SPF and DKIM are correct.

For example, some systems send on your behalf using IP addresses not listed in SPF, but DKIM passes. If your DMARC policy is set to reject and SPF fails, your email gets blocked. This happens often with ESPs that use their own IPs while signing with your domain’s DKIM key.

Use DMARC reporting (found in XML format at dmarc.org) to monitor authentication results. Check for alignment issues—where the From domain doesn’t match the SPF or DKIM domain—before enforcing strict policies.

Once SPF, DKIM, and DMARC are correctly set and aligned, your deliverability foundation shifts from fragile to reliable. Tools like MailTester's real-time verification API or inbox placement tester can check if these records are valid across major inboxes.

For campaigns, check your full email infrastructure before sending. Even one misaligned record can drop your Sender Score. Fixing this early avoids weeks of lost delivery and prevents reputation damage. It’s not optional—unless you want to send blind.

Use MailTester’s inbox-placement testing to confirm real improvements

If your Sender Score is below 70, cleaning your list and setting up authentication like SPF, DKIM, and DMARC are the right first steps—but they won’t tell you if your emails are actually landing in inboxes. Only inbox-placement testing with real consumer email providers can confirm whether those fixes are working in production. Let’s test it.

Verify the fix with actual inbox delivery

  • After fixing your list hygiene and email authentication, don’t assume the Sender Score will improve on its own—test it in real-world conditions.
  • Use MailTester’s inbox-placement tool to send a test email to real inboxes across Gmail, Yahoo, Outlook, and Apple Mail—no simulated or sandboxed environments.
  • The test shows true delivery rates and spam filter behavior, revealing if your domain or IP is still being blocked, quarantined, or marked as spam.
  • MailTester uses actual email providers’ infrastructure and filtering logic, which aligns with standards from the SMTP RFC 5321 and practices used by major inbox providers.
  • Compare results before and after fixes: a 5% lift in inbox placement doesn’t mean much if spam filter scores remain high—it’s the real inbox rate that matters.

Focus on what moves the needle

  • If your emails still land in spam folders after authentication and list cleaning, you’re likely dealing with poor sender reputation, suspicious content, or infrastructure issues like shared IPs.
  • MailTester’s inbox-placement results identify which inbox providers are rejecting or deprioritizing your messages—use that data to target the right fixes.
  • Run regular inbox tests after sending campaigns or making infrastructure changes to ensure your delivery stays stable.
  • Integrate MailTester with tools like Mailchimp, HubSpot, Klaviyo, or SendGrid to automatically verify emails before sending and test delivery in real time (Learn more about integrations).
  • To start testing, use the free tier of MailTester’s inbox placement tool and scale with credits that never expire (View pricing).

Once your Sender Score is above 70, sustain it with discipline

A Sender Score above 70 is a milestone, not a finish line. Deliverability is an ongoing condition, not a one-time fix.

Key practices for sustained delivery

  • Verify every new subscriber in real time using the MailTester API to prevent invalid addresses from entering your list.
  • Check bounce and complaint rates at least once a week—high rates signal emerging issues before they damage reputation.
  • Avoid sudden spikes in send volume. Warm up domains gradually over days, not hours, to build trust with mailbox providers.
  • Use the in-app AI assistant in MailTester to diagnose problems as they happen, based on real-time verification data and feedback loops.

Consistency beats intensity. The highest-performing senders treat reputation management as routine hygiene.

Sources

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Frequently asked questions

How long does it take to improve a Sender Score below 70?

Typically 7 to 21 days after cleaning your list, fixing authentication, and sending consistently at moderate volume.

Can I fix a Sender Score if my domain is on a blocklist?

Yes—but only after resolving the root cause (e.g., poor list hygiene or unauthorized sending). Clean the list first, then request delisting.

Is 98.9% accuracy in email verification really reliable?

Yes—MailTester’s 98.9% accuracy is based on real-world validation across major providers, and it’s independent of spam trap detection.

Do disposable emails hurt my Sender Score?

They don’t directly lower your score—but they increase bounce and spam complaint rates, both of which hurt reputation.

What’s the difference between a hard and soft bounce?

A hard bounce means the address is invalid or never existed. A soft bounce means temporary delivery failure (e.g., full inbox). Hard bounces are more harmful.

Should I avoid using role accounts like admin@ or sales@?

Yes—role addresses often lack engagement. They increase spam complaints and bounce rates, which lower reputation.

Can I re-verify a list after it’s been cleaned?

Yes—run a new verification after cleaning to confirm the list is fully valid and no new risks have entered.

Do I need to pay for MailTester to fix a low Sender Score?

No. You can start with 100 free verifications to test the system. Credits never expire, so you can scale gradually.

How does inbox-placement testing work?

It sends test emails to real inboxes across major providers and returns data on delivery, placement, and filtering status.

Can poor list hygiene cause a domain-wide Sender Score drop?

Yes—email providers rate entire domains. One bad list can trigger blocklists and affect all sending from that domain.

Does MailTester work with SendGrid and Mailchimp?

Yes—MailTester integrates with Mailchimp, HubSpot, Klaviyo, and SendGrid to verify addresses before sending.

Is a high Sender Score enough to guarantee inbox placement?

No—high Sender Score helps, but deliverability also depends on content, engagement, and list quality. It’s one factor, not a guarantee.