Ever sent an important email campaign only to wonder if it actually reached your recipients? You're not alone. For businesses relying on email marketing, few things are more frustrating than uncertainty about whether your messages are being delivered or blocked. We've seen firsthand how blocked emails can silently damage marketing results while leaving senders completely unaware.
Email blocking is a common issue that affects businesses of all sizes. When your emails get blocked, they never reach their intended recipients, not even the spam folder. This creates a significant blind spot in your marketing efforts.
In this guide, we'll show you how to identify if your emails are being blocked, understand why it happens, and implement effective solutions to get your messages flowing again. Let's solve this deliverability puzzle together.
What Does It Mean When Your Email Is Blocked?
Email blocking occurs when an email server or Internet Service Provider (ISP) prevents your message from reaching its intended recipient. Unlike bounced emails that return an error message, blocked emails often disappear without notification. This makes them particularly troublesome to identify.
The impact on your business can be substantial. When emails get blocked, you lose potential conversions, damage customer relationships, and waste marketing resources. According to industry data, the average email deliverability rate for marketing emails stands at 83.1%, meaning nearly 17% of emails fail to reach their destination, with 10.5% landing in spam folders and 6.4% going missing entirely. (Source: Email Tool Tester)
Understanding email blocking is the first step toward solving deliverability issues. Let's look at the two main types of email blocks you might encounter.
Hard Blocks vs. Soft Blocks
Email blocks generally fall into two categories: hard blocks and soft blocks. Each has different causes and implications for your email marketing efforts.
Hard blocks are permanent rejections. They occur when an email server decides never to accept messages from your sending address or domain. These blocks typically happen after repeated deliverability issues or serious violations of sending practices.
Soft blocks are temporary rejections. The receiving server may accept your emails again in the future if you address the underlying issues. These often result from temporary problems or minor policy violations.
Here's a comparison of hard blocks versus soft blocks to help you understand the differences:
Now that we understand what email blocking means, let's explore the warning signs that your emails might be getting blocked.
7 Common Signs Your Email Is Blocked
Detecting blocked emails isn't always straightforward. Here are the key indicators that can help you identify if your emails are being blocked before the problem severely impacts your marketing results.
1. Receiving Specific Bounce-Back Messages
The most direct indication comes from bounce-back notifications. While not all blocked emails generate these messages, many do provide error codes that can help diagnose the issue.
Pay close attention to the specific wording in these bounce messages. Phrases like "message rejected," "IP blacklisted," or "blocked for policy reasons" strongly suggest your email has been blocked rather than merely bouncing.
Different email providers use different error codes and messages. Here's what some common bounce-back messages might indicate:
2. No Response from Recipients
Sometimes silence speaks volumes. If you notice that recipients from specific domains (like gmail.com or yahoo.com) never respond to your emails, it could indicate a domain-specific block.
This pattern becomes particularly suspicious when it affects multiple recipients from the same domain. For example, if none of your gmail.com contacts ever reply, while contacts at other domains respond normally, Gmail might be blocking your messages.
To confirm this suspicion, try sending test emails to personal accounts at the suspected blocking domain. If these test messages also go unanswered, you likely have a domain-specific blocking issue.
3. Low Open Rates Across Campaigns
A sudden or persistent drop in email open rates often signals deliverability problems. While industry benchmarks vary, B2B email delivery rates for cold emails typically reach 98.16%, according to recent data. (Source: Truly Inbox)
If your open rates fall significantly below your historical average or industry benchmarks, it suggests your emails aren't reaching inboxes. This could be due to blocking or spam folder placement.
To identify potential blocking issues, segment your open rate data by email domain. A sharp decline in opens from specific domains points to potential blocking by those providers.
4. Unusual Spike in Bounce Rates
Most email marketing platforms track bounce rates automatically. A sudden increase in bounces, especially hard bounces, often indicates blocking issues.
Normal bounce rates typically range from 0.5% to 2% for healthy email lists. When bounce rates exceed 5%, it's a strong indicator of deliverability problems, including possible blocks.
What constitutes a concerning bounce rate varies by industry. Here's a breakdown of average bounce rates by sector:
5. Inability to Reach Specific Domains
If you notice that recipients from certain email domains (like gmail.com, yahoo.com, or specific company domains) never receive your messages, you might be experiencing domain-specific blocking.
Domain-specific blocks occur when a particular email provider identifies your sending domain or IP address as problematic. Each email service provider has different thresholds and criteria for blocking senders. For example, Gmail achieves a 95.54% overall deliverability rate, with 57.8% of emails reaching the primary inbox and 37.74% going to the promotions tab. (Source: Email Tool Tester)
To confirm domain-specific blocking, send test emails to addresses at the suspected blocking domain and track their delivery. If the tests consistently fail while emails to other domains succeed, you've identified a domain-specific block.
6. Increased Spam Complaints
Most email service providers track and report when recipients mark your emails as spam. A rise in spam complaints often triggers automated blocks by email providers.
Even a seemingly small complaint rate can cause problems. Generally, spam complaint rates above 0.1% (1 complaint per 1,000 emails) can trigger deliverability issues and potential blocks.
Monitor your spam complaint rate closely. If it rises above industry standards, take immediate action to address the underlying causes before blocking occurs.
7. Being Added to Email Blacklists
Email blacklists are databases of IP addresses and domains flagged for sending unwanted emails. Being added to major blacklists almost guarantees delivery problems, including outright blocking by many email providers.
Regularly checking your blacklist status is essential for maintaining good deliverability. If you discover your domain or IP on a blacklist, you'll need to follow that blacklist's removal procedures to resolve the issue.
Several free and paid tools allow you to check your blacklist status across multiple databases simultaneously. We recommend checking at least monthly, or immediately if you notice other signs of email blocking.
How to Confirm If Your Email Is Blocked
When you suspect your emails are being blocked, it's important to confirm the issue before taking corrective action. Here's how to systematically diagnose email blocking problems.
Tools for Checking Email Deliverability Status
Several specialized tools can help you determine if your emails are being blocked. These tools provide insights into deliverability issues that might not be apparent from your email marketing platform's analytics.
Email deliverability testing tools work by sending test emails to seed addresses across multiple email providers and analyzing their delivery success. These tests can reveal if your emails are being blocked, filtered to spam, or delivered successfully.
Here's a comparison of popular tools for checking email deliverability:
Conducting Controlled Test Sends
Beyond using specialized tools, you can conduct your own controlled tests to identify blocking issues. This approach helps pinpoint specific problems, especially with particular domains or providers.
Start by creating test email accounts across major providers (Gmail, Outlook, Yahoo, etc.). Send identical test messages to each account and track which ones arrive, which go to spam, and which never appear at all.
For best results, include these elements in your test:
- Send from the exact domain and email address you normally use
- Use similar content to your regular emails
- Send at different times of day
- Try both simple and more complex messages
- Track results meticulously
Document your findings carefully. If emails consistently fail to arrive at certain providers, you've confirmed a blocking issue with those specific providers.
Common Reasons Why Emails Get Blocked
Understanding why emails get blocked is crucial for implementing effective solutions. Most blocks occur for specific, identifiable reasons that you can address.
Sender Reputation Issues
Sender reputation is a score that email providers assign to your sending domain and IP address. Poor reputation scores often lead to blocking or filtering to spam folders.
Multiple factors affect your sender reputation, including:
- Past sending behavior and compliance with email best practices
- Spam complaint rates from your recipients
- Engagement metrics (opens, clicks, replies)
- Bounce rates and invalid addresses
- Sending volume and consistency
Your sending reputation develops over time based on these factors. Once damaged, repairing it requires consistent good practices over weeks or months.
You can check your sender reputation using tools like Google Postmaster Tools, Microsoft SNDS, or third-party reputation monitoring services. These tools provide insights into how major email providers view your sending practices.
Content-Related Triggers
The content of your emails can trigger blocking, even if your sender reputation is good. Modern spam filters analyze numerous content elements to determine whether to deliver, block, or filter messages.
Common content issues that trigger blocks include:
Content filtering has become increasingly sophisticated. What might have worked in the past could now trigger blocking, so staying current with best practices is essential.
Technical Configuration Problems
Technical issues often cause email blocking, especially for businesses that don't have specialized email delivery expertise. These problems relate to how your email infrastructure is configured.
Common technical issues include:
Authentication failures: Without proper SPF, DKIM, and DMARC records, email providers may block your messages as potentially fraudulent. These authentication protocols verify that emails actually come from who they claim to be from.
IP reputation problems: If you send from an IP address with a history of spam or one shared with problematic senders, you may experience blocks.
Improper DNS configuration: Errors in your domain's DNS settings can prevent proper email authentication and lead to blocking.
With the global volume of email reaching 376 billion messages sent daily as of 2025, email providers must use technical checks to filter out unwanted messages. (Source: Omnisend)
Solutions to Fix Blocked Emails
Now that we understand the common causes of email blocking, let's explore effective solutions to get your emails flowing again.
Improving Your Sender Reputation
Repairing a damaged sender reputation takes time and consistent good practices. Here are steps to improve your reputation:
Start small and gradually increase volume. If you've been blocked, begin sending to your most engaged subscribers only. As delivery improves, slowly expand to less engaged segments.
Focus on engagement. Send content that encourages opens, clicks, and replies. Higher engagement rates signal to email providers that your messages are wanted.
Remove unengaged subscribers. Recipients who never open your emails hurt your engagement metrics and increase the risk of being marked as spam.
Maintain consistent sending patterns. Sudden spikes in volume can trigger blocking. Establish a regular sending schedule and stick to it.
Repairing your sender reputation typically takes 4-8 weeks of consistent good practices. Be patient and monitor your progress using sender reputation tools.
Email List Hygiene Best Practices
Email list hygiene is crucial for preventing blocks. Clean lists have fewer bounces, better engagement, and lower complaint rates.
Implement these list hygiene practices:
Regularly remove invalid and inactive addresses. Addresses that haven't engaged with your emails in 6-12 months should be removed or put into a re-engagement campaign.
Verify new email addresses before adding them to your list. Using an email verification service can identify invalid addresses before they damage your reputation.
Use double opt-in for new subscribers. This confirms the address is valid and that the owner actually wants your emails.
Segment your list based on engagement. Sending to highly engaged subscribers first helps build positive sending history.
Automated solutions like mailfloss can simplify list hygiene by automatically cleaning your email lists daily. This prevents invalid emails from accumulating and risking your sender reputation.
Technical Solutions and Authentication
Proper technical configuration is essential for avoiding blocks. Implement these technical solutions:
Set up proper authentication. Configure SPF, DKIM, and DMARC records for your sending domain. These protocols verify your identity to receiving email servers.
Use a dedicated IP address for sending. This separates your reputation from other senders and gives you more control.
Implement proper feedback loops. These alert you when recipients mark your emails as spam, allowing you to remove those addresses.
Monitor your IP and domain reputation. Tools like Google Postmaster Tools provide insights into how your sending infrastructure is perceived.
If technical configuration sounds overwhelming, consider working with an email deliverability specialist or using a reputable email service provider that handles these elements for you.
Content Optimization Strategies
Optimizing your email content reduces the risk of content-based blocks:
Avoid spam trigger words and phrases. Terms like "free," "guarantee," "no risk," and excessive punctuation (!!!) can trigger filters.
Maintain a good text-to-image ratio. Aim for at least 60% text to 40% images.
Use clear, honest subject lines. Misleading subjects generate complaints and blocks.
Balance link usage. Too many links, especially to unfamiliar domains, can trigger filters.
Test your content before sending. Use spam testing tools to identify potential content issues before sending to your full list.
Remember that what happens if you misspell an email address can also impact deliverability, as typos in domains can lead to invalid addresses that damage your sender reputation.
How mailfloss Can Help Prevent Email Blocking
At mailfloss, we've designed our service specifically to help businesses avoid the deliverability issues that lead to email blocking. Our automated tools work proactively to maintain clean lists and improve delivery rates.
Automated Email Verification Features
Our email verification system helps prevent blocks before they happen by:
Automatically removing invalid email addresses from your lists daily. This prevents the high bounce rates that damage sender reputation and trigger blocks.
Conducting over 20 different checks on each email address to ensure it's valid and deliverable. This thorough approach catches problems that simpler verification methods miss.
Integrating seamlessly with 35+ popular email service providers, including Mailchimp, HubSpot, ActiveCampaign, and many others. This makes implementation effortless with a simple one-time setup.
Working continuously in the background. Once set up, mailfloss automatically cleans your lists without requiring ongoing manual effort.
Our verification process identifies and removes various problematic address types, including non-existent addresses, disposable emails, and toxic addresses that could harm your reputation.
Real-Time Typo Correction
One of our standout features is real-time typo correction. This technology:
Automatically fixes common typos in email domains like "gmal.com" instead of "gmail.com" or "yaho.com" instead of "yahoo.com".
Works with major email providers including Gmail, Hotmail, Yahoo, and AOL.
Operates automatically without requiring manual intervention.
Recovers potentially lost contacts who would otherwise be unreachable due to simple typing errors.
Understanding what is a soft bounce in email marketing helps explain why typo correction is so valuable. Soft bounces can eventually convert to hard bounces if left unaddressed, and typo correction prevents this progression.
Preventative Measures for Long-Term Email Deliverability
Beyond fixing existing blocks, implementing preventative strategies helps maintain good deliverability over time.
Regular Monitoring Practices
Consistent monitoring helps catch potential problems before they lead to blocks:
Track key deliverability metrics. Regularly monitor open rates, click rates, bounce rates, and complaint rates for signs of trouble.
Check blacklist status weekly. Use tools like MXToolbox or MultiRBL to verify your domain and IP addresses aren't listed on any blacklists.
Review engagement metrics by domain. Look for patterns where specific email providers (Gmail, Yahoo, etc.) show lower engagement, which might indicate filtering.
Test deliverability regularly. Send test emails to seed accounts at various providers to confirm your messages are reaching inboxes.
Set up alerts for unusual metrics. Configure notifications for sudden changes in bounce rates or complaint rates that might indicate blocking.
Quality benchmarks suggest that email deliverability rates above 89% are considered good, while rates above 95% are excellent. Rates below 80% indicate poor deliverability that requires immediate attention. (Source: Email Tool Tester)
Maintaining a Healthy Email List
A clean, engaged email list is your best defense against blocking:
Implement a sunset policy. Automatically remove subscribers who haven't engaged with your emails after a set period (typically 6-12 months).
Use confirmed opt-in processes. Verify that subscribers genuinely want your emails by requiring them to confirm their subscription.
Segment based on engagement. Send more frequently to engaged subscribers and less frequently to those with lower engagement.
Make unsubscribing easy. A clear, simple unsubscribe process reduces spam complaints that can trigger blocks.
Regularly clean your list using an automated service like mailfloss to remove invalid addresses before they cause problems.
Email delivery rates can significantly impact your marketing ROI, making these preventative measures a worthwhile investment for any business relying on email communication.
Conclusion
Email blocking can significantly impact your marketing effectiveness, but it doesn't have to be a permanent roadblock. By recognizing the signs of blocked emails, understanding the causes, and implementing the solutions we've outlined, you can restore and maintain healthy email deliverability.
Remember that good email deliverability requires ongoing attention. Regular list cleaning, proper authentication, content optimization, and consistent monitoring all play important roles in keeping your emails flowing to inboxes.
At mailfloss, we're committed to helping businesses solve email deliverability challenges. Our automated email verification and typo correction tools provide a simple, effective way to prevent many of the issues that lead to email blocking.
Ready to improve your email deliverability and stop worrying about blocked emails? Try mailfloss today and see the difference that automated email verification can make for your business.
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