Email Blocked: Reasons and Fixes

Introduction

Email marketing remains one of the most cost-effective channels for businesses. However, this success hinges on email deliverability—the ability to land messages in recipients’ primary inboxes. When emails are blocked or filtered into spam folders, even the best campaigns fail. Studies show that 20% of legitimate emails never reach inboxes due to technical missteps, spam triggers, or poor sender reputations.

What Does “Email Blocked” Mean?

A blocked email is one that never reaches the recipient due to rejection by email providers (e.g., Gmail, Outlook) or spam filters. This can happen at two stages:

Hard Bounce: The recipient’s server permanently rejects the email (e.g., invalid address).

Soft Bounce: Temporary rejection due to issues like a full inbox or server downtime.

Impact on Marketing Efforts

Blocked emails waste resources, damage sender reputations, and reduce ROI. For instance, if 30% of your emails are blocked, your campaign’s effectiveness plummets, and repeated blocks can land your domain on blacklists like Spamhaus.

Why Emails Get Blocked And How To Fix it

1. Lack of Authentication

One of the main reasons for blocking email is the lack of proper authentication. Without implementing email authentication protocols such as SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance), email providers may treat your emails as suspicious. This can lead to lower deliverability rates and potential blockage.

How to fix it: Implement the right protocols

To address this issue, it's important to implement the proper authentication protocols. SPF verifies that the sending server is authorized to send emails on behalf of the domain. DKIM adds a digital signature to the email to verify its integrity and authenticity. DMARC helps prevent email spoofing and provides instructions on how to handle emails that fail authentication. By implementing these protocols and regularly monitoring and updating your authentication records, you can improve your email deliverability and avoid blockage.

2. Spammy Content

Emails that contain spammy content or trigger words can be flagged by spam filters, leading to lower deliverability rates and potential blockage. Phrases like "limited-time offer" or excessive use of exclamation marks can raise red flags for spam filters.

How to fix it: Improve your content

To address this issue, it's important to improve your email content. Avoid using overly promotional language, excessive capitalization, and an overload of exclamation points or emojis. Instead, opt for a more natural and conversational tone. Test your email templates to ensure they work across all email clients, are mobile-friendly, and follow accessibility best practices. Segment your subscribers based on their demographic information and past behavior to deliver personalized and relevant content.

3. Spam Traps

Spam traps are email addresses used by email providers to identify senders with poor list hygiene. They can be recycled or pristine trap addresses that catch senders who have not maintained a clean and healthy email list. Falling into a spam trap can have a significant impact on deliverability.

How to fix it: Practice list hygiene

To avoid hitting spam traps, it's important to practice good list hygiene. Regularly clean your email list to remove unengaged or invalid subscribers. Avoid purchasing email lists, as they may include spam trap addresses. Implement double opt-in confirmation and make it easy for subscribers to unsubscribe if they wish. Monitor feedback loops to identify and address any issues that lead to complaints. Checking your email or IP address against email blocklists can also help ensure your reputation remains intact.

4. Custom Spam Filters

Some organizations have custom spam filters in place, which can be more aggressive than standard mailbox provider filters. These filters may block emails based on sender reputation or content.

How to fix it: Bypass custom filters

To bypass custom spam filters, it's important to understand the specific filters used by your recipients' companies and tailor your emails accordingly. Conduct A/B testing to identify subject lines and content that are more likely to get through. Additionally, encourage subscribers to whitelist your domain by including "Add to Contacts" prompts in your emails.

5. Technical Issues

Technical issues with your emails can also lead to blockage. This can include broken HTML, oversized images, or non-mobile-responsive designs. These issues can trigger spam filters or cause rendering problems, resulting in lower deliverability rates.

How to fix it: Follow technical best practices

To address technical issues, it's important to follow best practices for email design and formatting. Use pre-built email templates that are mobile-optimized and follow industry standards. Test your emails across different email clients and devices to ensure they render correctly. Avoid using risky code such as JavaScript or Flash, and limit the number of links in your emails. By adhering to proper formatting guidelines, you can improve deliverability and avoid technical issues.

6. Repeatedly Sending to Invalid Addresses

Sending emails to invalid or non-existent email addresses can harm your sender reputation and lead to blockage. High hard bounce rates, which occur when emails fail to deliver due to invalid addresses, indicate poor list hygiene.

How to fix it: Validate and clean your email list

To avoid sending emails to invalid addresses, it's important to validate and clean your email list regularly. Implement real-time address verification tools to check the syntax, domain validity, and mailbox activity of email addresses. Mailgo's email verification tool can help identify and remove invalid addresses from your list. Additionally, automatically suppress addresses with a high bounce rate to maintain list hygiene and improve deliverability.

7. Formatting Problems

Formatting issues in your emails, such as hidden text, mismatched fonts, or excessive links, can raise red flags for spam filters and mailbox providers. These issues can make your emails appear suspicious or unprofessional.

How to fix it: Follow formatting best practices

​​To address formatting problems, it's important to follow best practices for email formatting. Avoid using hidden text or mismatched fonts, as they can trigger spam filters. Limit the number of links in your emails and ensure they are relevant and necessary. By adhering to proper formatting guidelines, you can improve deliverability and avoid formatting-related blockage.

8. High Bounce Rate

A high bounce rate, which occurs when emails fail to deliver to the recipient, can harm your sender reputation and lead to blockage. Bounces can be classified as hard bounces, which are permanent failures due to invalid or non-existent email addresses, or soft bounces, which are temporary failures due to issues like a full mailbox or technical problems.

How to fix it: Reduce your bounce rate

To reduce your bounce rate, it's important to maintain a clean and healthy email list. Implement list hygiene practices such as regularly validating email addresses and removing inactive or invalid ones. Use email verification tools to ensure the validity of email addresses before adding them to your list. Segment your email lists and prioritize active subscribers to reduce bounce rates. By focusing on list hygiene and reducing bounces, you can improve your sender reputation and deliverability.

Best Practices To Avoid Getting Blocked

Write Valuable Emails

To improve email deliverability, it's important to be a good digital citizen and follow best practices. One way to achieve this is by sending relevant and personalized content to your subscribers. Mailgo's AI content generation feature can pull data from platforms like company websites to help you create more targeted and personalized emails. Additionally, avoid sending emails at odd hours that may disrupt recipients. Utilize mailgo's Smart Scheduling feature to send emails at the optimal time, such as 10 AM local time, to increase engagement.

Monitor Sender Reputation

Maintaining a good sender reputation is crucial for email deliverability. Always remember to track the health of your IP address and domain. Focus on important metrics such as spam complaints and bounce rates, allowing you to monitor and address any issues that may affect your sender reputation. By actively managing your sender reputation, you can improve deliverability and ensure your emails reach the inbox.

Leverage Email Warm-up Strategies

Email warm-up is a crucial step in establishing a good sender reputation and improving deliverability. Mailgo's email warm-up feature gradually increases the sending volume from new domains, mimicking natural human behavior and building trust with email providers. This process helps avoid sudden spikes in email activity that could trigger spam filters or lead to blockage. By utilizing mailgo's email warm-up strategies, you can improve your sender reputation and ensure your emails reach the inbox.

Conclusion

In conclusion, improving email deliverability and overcoming email blockage is achievable with the right approach. By focusing on addressing authentication gaps, refining content, and maintaining clean email lists, businesses can achieve a deliverability rate of 90% or higher. Tools like mailgo provide AI-driven solutions that simplify the process and enhance email deliverability.

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