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Email Deliverability Issues: The Most Common Problems To Fix

The journey from hitting ‘send’ to landing in your subscriber’s inbox has many potential pitfalls. This journey, known as email deliverability, is a critical factor in the success of your email marketing efforts. But what happens when your carefully crafted emails don’t reach their intended destination? What if they end up in the spam folder or, worse, get blocked entirely?

In this article, we’ll uncover the most common issues that can hamper your emails’ deliverability, from poor list hygiene and low engagement rates to high complaint rates and block listings.

We’ll also provide insights into more technical aspects like IP and domain reputation issues, volume spikes, and the dreaded spam trap hits. Each section not only highlights the problem but also offers actionable solutions to help you navigate these challenges and improve your email deliverability.

So, whether you’re a seasoned email marketer or just getting started, this comprehensive guide will equip you with the knowledge and tools to ensure your emails reach their intended destination – your subscribers’ inboxes. Let’s dive in and start fixing those deliverability issues!

Note: If you are ready to take control of your email deliverability, start by running a test email through MailGenius. This powerful tool will analyze your emails, identify potential deliverability issues, and provide actionable feedback to help you improve.

Don’t let your carefully crafted emails go unnoticed in the spam tab. Use MailGenius to fine-tune your email strategy, test your inbox placement, improve your deliverability, and increase your chances of landing in the primary inbox.

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Why Does Email Deliverability Matter?

Email deliverability is the measure of your ability to get your emails into your subscribers’ inboxes, rather than being relegated to the spam folder or blocked entirely. It’s the cornerstone of successful email marketing. But why is deliverability important and how come it matters so much? Here’s why:

  • Direct Impact on ROI: Your email marketing campaigns can only generate a return on investment if your emails reach your subscribers. Every email that doesn’t make it to the inbox is a missed opportunity to engage a potential customer, drive traffic to your site, and ultimately, make a sale.

  • Reputation Management: Your sender reputation, a score assigned by an ISP which stands for Internet Service Providers, is heavily influenced by your email deliverability. A poor sender reputation can lead to your emails being blocked by ISPs. This not only affects your current email marketing efforts but can also have long-term consequences for future campaigns.

  • Subscriber Engagement: Deliverability issues can lead to lower open rates and engagement. If your emails are consistently landing in the spam folder, your subscribers may miss out on your content entirely. This can lead to decreased engagement, lower click-through rates, and ultimately, a decrease in conversions and sales.

  • Customer Relationships: Email is a personal channel, often used for one-on-one communication. When your emails land in your subscribers’ inboxes, you’re in their personal space, which can help build stronger relationships. However, consistent deliverability issues can break this trust and harm your relationship with your subscribers.

  • Regulatory Compliance: ISPs aren’t the only ones watching your email practices. Regulatory bodies also have rules about spam and unsolicited emails. Consistent deliverability issues could indicate that you’re not following these rules, which could lead to penalties. Always have a visible unsubscribe link when you send emails.


What Negative Factors Affect Email Deliverability? The Most Common Issues To Repair

Email deliverability issues can significantly impact your email marketing efforts. Here are some of the most common problems that you need to address to ensure your emails reach your subscribers’ inboxes:

Poor List Hygiene

Maintaining a clean and healthy email list is fundamental to successful email marketing. However, poor list hygiene is a common issue that can significantly impact your email deliverability.

Invalid Addresses

One of the main culprits of poor list hygiene is sending emails to invalid addresses. These could be email addresses that were never active, abandoned, or incorrectly entered into your database. An email sent to an invalid address results in a ‘hard bounce’ or a permanent delivery failure. A high hard bounce rate is a red flag to ISPs and can harm your sender reputation. If your hard bounce rates rise above 5% in any given month, it’s a signal that your list has a significant issue that needs to be addressed.

Old or Inactive Addresses

Another aspect of poor list hygiene is the presence of old or inactive addresses on your list. Subscribers who haven’t engaged with your emails for a long time can negatively impact your engagement rates, which in turn can affect your deliverability. Regularly cleaning your list of inactive subscribers can help maintain a high engagement rate and improve deliverability.

Purchased or Rented Lists

Using rented or purchased lists for email marketing can also lead to poor list hygiene. These lists often contain outdated or irrelevant email addresses, leading to high bounce rates and low engagement. They can also increase spam complaints, as recipients did not opt-in to receive your emails. It’s always best to build your email list organically through legitimate opt-in methods.

Lack of Segmentation

Sending the same email to everyone on your list, regardless of their interests or engagement level, can lead to lower open and unsubscribe rates. This lack of segmentation can be seen as a form of poor list hygiene. You can improve engagement and deliverability by segmenting your list and tailoring your emails to different segments.

No Regular Audits

Regularly auditing your email list is crucial to maintaining good list hygiene. This involves removing hard bounces, unsubscribes, and inactive subscribers and correcting any obvious typos in email addresses. Regular audits can help keep your list clean and improve your overall deliverability.


High Complaint Rates

Complaint rates, or the percentage of your emails that recipients mark as spam, play a significant role in your email deliverability. High complaint rates can be a serious issue, indicating that your emails are not meeting your subscribers’ expectations or are perceived as unwanted.

Each time a recipient marks your email as spam, it sends a negative signal to ISPs about your email practices. High complaint rates can harm your sender reputation, a score assigned by ISPs based on your email sending behavior. A poor sender reputation can block your emails or land in the spam folder, significantly impacting your email deliverability.

We always recommend to try different email testing tools to see your inbox placement.

Benchmark for Complaint Rates

While the acceptable complaint rate can vary depending on the industry and the ISP, most brands are able to keep their complaint rates well below 0.2%. If your complaint rates exceed this level, it’s a serious sign of trouble and immediate action should be taken to address the issue.

Causes of High Complaint Rates

Several factors can cause high complaint rates. These include sending irrelevant or too many emails, not using clear and easy unsubscribe methods, or using misleading subject lines. Another common cause is the use of purchased or rented email lists, where recipients did not opt-in to receive emails from you.

Addressing High Complaint Rates

To reduce complaint rates, respecting your subscribers’ preferences and providing them with relevant and valuable content is crucial. This includes using clear and concise subject lines, providing an easy unsubscribe option, and ensuring your emails provide value to the recipient. Regularly reviewing your complaint rates and taking action when they start to rise can help maintain your sender reputation and improve your email deliverability.

Many mailbox providers offer a feedback loop service that notify you about recipient complaints (FBL reports). It is important to promptly remove recipients who have complained from your mailing list to prevent further mailings to them through your automated systems. Treating a complaint as an unsubscribe request is crucial in maintaining a positive sender reputation and ensuring effective email communication.

Too Much Promotional Content

Promotional content typically includes language of sales pitches, special offers, and advertisements. While this type of content can be effective in driving sales and conversions, it can also trigger email spam filters if not handled properly. This is because spam filters are designed to protect email users from unsolicited and irrelevant content, which often includes overly promotional material.

On the other hand, non-promotional content provides value to the reader without directly selling a product or service. Non-promotional content is less likely to trigger spam filters and more likely to engage your audience, which can improve your email deliverability.

It’s crucial to avoid using common spam trigger words in your emails. Spam trigger words are terms that are commonly associated with spammy content and can cause your emails to be flagged by spam filters. These can include phrases like “buy now”, “free”, “guarantee”, “no obligation”, “risk-free”, and many others. Using these words in your subject lines or email content can increase the chances of your emails being marked as spam, which can harm your email deliverability.

Try MailGenius to send a free test email, receive feedback on deliverability issues, and improve your chances of landing in the primary inbox.

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IP and Domain Reputation Issues

The reputation of your IP address and domain plays a crucial role in your email deliverability. ISPs use this reputation to determine whether your emails are trustworthy or potentially harmful.

Your IP reputation is based on the history of your IP address’s email-sending behavior, while your domain reputation is tied to your domain’s email activity. Both reputations are used by ISPs to decide where to place your emails – in the inbox, or recipient’s spam folder, or to block them entirely.

Impact on Deliverability

A poor IP or domain reputation can significantly impact your email deliverability. If ISPs perceive your IP or domain as untrustworthy due to a history of spammy behavior, they may block your emails or send them to the spam folder, reducing the chances of your emails reaching your subscribers’ inboxes.

Changing Email Service Providers

If you’ve recently changed your Email Service Provider, you’re essentially starting from scratch with new IP addresses and a new sending subdomain, neither of which have a reputation associated with them. This change can temporarily affect your deliverability until you establish a positive reputation with your new IP and domain.

Warming Up a New IP or Domain

When you start sending emails from a new IP address or domain, you need to ‘warm it up’ by gradually increasing your email volume. This gives ISPs time to recognize that the new IP or domain is trustworthy. Sending too many emails too quickly from a new IP or domain can lead to deliverability issues.

Addressing IP and Domain Reputation Issues

To maintain a good IP and domain reputation, following best email practices is crucial. This includes maintaining a clean email list, low complaint rates, and avoiding spammy behavior. Regularly monitoring your IP and domain reputation can also help you identify and address any potential issues before they significantly impact your deliverability.

it’s advised to implement SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) records for your domain. These email authentication methods work at the DNS level, enabling other servers to validate your emails and prevent fake emails from domains posing as your own.

Note: Improve your email deliverability with our practical guide! Take advantage of valuable insights and run an email deliverability audit to optimize your sender reputation and ensure successful inbox placement. Enhance your email marketing effectiveness today by accessing our comprehensive guide. Gain control over your email deliverability and maximize the impact of your email campaigns. Get started now and unlock the secrets to successful email communication.

Volume Spikes

Consistency is key in email marketing, and sudden spikes in email volume can raise red flags with ISPs, potentially leading to deliverability issues.

A volume spike refers to a sudden increase in the number of emails you send within a short period. This could be due to a special promotion, a seasonal event, or an ad-hoc email campaign. While these spikes can be part of your marketing strategy, they can also trigger spam filters if not managed properly.

Impact on Deliverability

ISPs monitor email volume as part of their spam detection algorithms. A sudden spike in volume can be seen as a sign of spamming activity, leading ISPs to block your emails or send them to the spam folder. This can significantly impact your email deliverability and the success of your email campaign.

Managing Volume Spikes

Maintaining a consistent email sending schedule is crucial to manage volume spikes. If you need to increase your volume, do so gradually over time to avoid triggering spam filters. It’s also important to closely monitor your deliverability metrics during high-volume periods to quickly identify and address potential issues.

Volume spikes are common during peak seasons when many businesses increase their email frequency. However, this is also when ISPs are on high alert for spam activity. Planning your peak season email campaigns carefully is important to avoid sudden volume spikes that could harm your deliverability.


Being listed on a blacklist is a serious issue that can significantly impact your email deliverability.

A blacklist is a list of IP addresses or domains that have been reported or observed sending spam or unwanted emails. ISPs use these lists to help determine whether to deliver, block, or flag an email as spam. If your IP or domain is listed on a blacklist, a significant portion of your emails could be blocked or sent to the spam folder.

You can use our blacklist checker to see if you are listed and your emails are blocked.

Impact on Deliverability

Depending on the blacklist and the ISP, your emails could be blocked entirely, significantly reducing the number of emails that reach your subscribers’ inboxes. This can harm your engagement rates, conversions, and overall email marketing ROI.

Some blacklists, like Spamhaus, are widely used by ISPs and can significantly impact your deliverability. Even an informational listing from Spamhaus, which is a warning that a formal listing is likely to happen if you don’t take action, should be taken seriously.

Causes of Blacklisting

Common causes of blacklisting include high complaint rates, high bounce rates, hitting spam traps, and other spammy behavior. Maintaining good email practices can help avoid blacklisting.

Addressing Blacklisting Problems

If you find that your IP or domain is listed on a blacklist, it’s crucial to take immediate action. This typically involves identifying and addressing the issue that led to the blacklisting, such as reducing complaint rates or improving list hygiene. Once you’ve addressed the issue, you can then request to be delisted.

Spam Trap Hits

Spam traps are a tool used by ISPs and blacklist providers to identify and track spammers. Hitting these traps can have serious consequences for your email deliverability.

Spam traps are email addresses that are specifically set up to catch spammers. They’re not used for regular email communication and don’t belong to real users. There are two main types of spam traps: pristine traps, which are email addresses that have never been used and are typically hidden on websites and scraped by spammers, and recycled traps, which are old email addresses that are no longer in use by the original owner and have been repurposed as a trap. 

That’s why you should always find spam trap email addresses and remove them from your email list.

Impact on Deliverability

Hitting a spam trap is a clear sign to ISPs and blacklist providers that your list hygiene practices are not up to par. Since spam traps are not used for regular communication, any emails sent to them are considered unsolicited and a form of spam. If you hit a spam trap, it can lead to severe deliverability issues, including being blacklisted.

Causes of Spam Trap Hits

Common causes of hitting spam traps include poor list hygiene, such as not regularly cleaning your list of inactive or invalid email addresses, and using purchased or rented email lists, which often contain spam trap addresses.

Addressing Spam Trap Hits

If you’ve hit a spam trap, it’s crucial to take immediate action to address the issue. This typically involves thoroughly auditing your email list to identify and remove any potential spam trap addresses. It’s also important to review your list acquisition practices to ensure you’re only adding valid, opt-in addresses to your list.

It’s Time To Fix Deliverability Issues!

Navigating the complex landscape of email deliverability can be a challenging task, but it’s an essential one for the success of your email marketing efforts. As we’ve explored in this comprehensive guide, numerous factors can impact whether your emails reach your subscribers’ inboxes or end up in the spam folder, or worse, get blocked entirely.

From maintaining good list hygiene and boosting engagement rates to managing your IP and domain reputation, addressing volume spikes, avoiding blocklistings, and steering clear of spam traps, each aspect plays a crucial role in your overall email deliverability.

Remember, the key to successful email marketing isn’t just about crafting compelling content; it’s about ensuring that your emails are delivered to the right place at the right time. Understanding and addressing the common deliverability issues outlined in this guide can significantly improve your email deliverability, leading to higher engagement, stronger customer relationships, and a better return on your email marketing investment.

So, it’s time to roll up your sleeves and start fixing those deliverability issues! With the knowledge and tools provided in this guide, you’re well-equipped to ensure that your emails reach their intended destination – your subscribers’ inboxes. Happy emailing!

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