Common Email Deliverability Issues and Fixes
Email deliverability is all about ensuring your emails land in inboxes - not spam folders. In 2025, with over 376 billion emails sent daily, nearly 17% of them either go undelivered or end up in spam. This affects businesses heavily, reducing engagement and damaging sender reputations. Here's a quick breakdown of key issues and solutions:
Common Problems:
- Spam traps: Outdated or invalid email addresses that harm your reputation.
- Authentication failures: Misconfigured SPF, DKIM, or DMARC records.
- Damaged sender reputation: High bounce rates, spam complaints, or low engagement.
- Spam-triggering content: Overly salesy language, poor formatting, or excessive links.
- Technical setup issues: Incorrect DNS settings or legacy infrastructure.
Fixes:
- Clean your email lists: Remove invalid addresses and inactive subscribers regularly.
- Set up proper authentication: Configure SPF, DKIM, and DMARC correctly.
- Monitor sender reputation: Track bounce rates, complaints, and engagement.
- Optimize email content: Avoid spammy language and test for issues before sending.
- Audit infrastructure: Ensure DNS settings and email systems are properly configured.
To improve deliverability, focus on maintaining clean lists, setting up authentication, and monitoring engagement metrics. Tools like Mailforge can simplify technical setups and help manage large-scale campaigns efficiently.
Common Email Deliverability Problems
Email deliverability issues can quietly derail your campaigns, leading to lost opportunities and wasted efforts. Let’s dive into some of the most common problems and their causes.
Spam Traps and Invalid Email Addresses
Spam traps are a major pitfall for email senders, often targeting those who rely on outdated, purchased, or scraped email lists. These traps come in different forms:
- Pristine traps: Addresses never used for legitimate communication.
- Repurposed traps: Previously valid addresses now used to identify spammers.
- Typo-based traps: Addresses with accidental errors, like "gmial.com" instead of "gmail.com."
"When a sender emails a spam trap, mailbox providers flag them as untrustworthy. This damages their sender reputation, causing more of their emails to land in recipients' spam folders or even get blocked entirely." – Daria Roshchyna, Technical Content Writer @Mailtrap
The consequences of hitting a spam trap are severe. It can lead to blacklisting of your IP address or domain, plummeting your deliverability rates. Compounding the issue, some email providers convert inactive email addresses into spam traps without prior notice.
Email Authentication Failures
Authentication issues are another common culprit. Misconfigurations in SPF, DKIM, or DMARC records can delay or block email delivery altogether. These failures often stem from:
- Misconfigured DKIM settings or mismatched keys.
- SPF issues, such as omitted sending servers or altered message headers.
- Problems caused by email forwarding or third-party misalignments.
Domain spoofing - where attackers impersonate your domain - can also trigger authentication failures. And with stricter requirements introduced in February 2024 by inbox providers like Google and Yahoo, proper DKIM and DMARC setups are now essential for bulk email senders.
"Email authentication is an essential but often misunderstood aspect of email security - and the consequences of neglecting it can be severe." – Margaret Wolfenden, Email Strategist, Validity
Damaged Sender Reputation
Think of your sender reputation as your email’s “credit score.” Providers monitor your email behavior and assign a score that influences whether your messages land in the inbox or get filtered out. Key factors that can harm your reputation include:
- High bounce rates or spam complaints.
- Low engagement metrics, like poor open or click-through rates.
- Technical issues, such as sending from blacklisted IPs or domains.
When recipients flag your emails as spam, it sends a strong negative signal to providers. Rebuilding a damaged reputation isn’t quick - it requires weeks or even months of consistent, responsible practices.
Content That Triggers Spam Filters
Spam filters are smarter than ever, using advanced algorithms to scrutinize your email content. Certain elements can immediately raise red flags, such as:
- Excessive capitalization or multiple exclamation marks (e.g., "URGENT!!!").
- Overly salesy language or spammy phrases.
- Poorly formatted HTML, too many links (especially shortened ones), or large images with minimal text.
Even legitimate emails can get flagged if they resemble common spam patterns, so balancing your content is key.
Poor Email Infrastructure Setup
Technical misconfigurations in your email infrastructure can also sabotage deliverability. Issues like incorrect DNS settings, shared IP addresses, or outdated systems can harm your campaigns. These problems become even more critical when managing multiple domains or scaling your email operations.
Legacy infrastructure, insufficient IP warming, or neglecting proper domain configurations can all lead to rejections or filtering. For large-scale outreach, these challenges are magnified. Tools like Mailforge simplify this process by offering automated DNS setup, advanced deliverability features, and streamlined bulk management, ensuring your infrastructure is optimized for success.
How to Fix Email Deliverability Issues
Now that we've covered the common problems, let’s dive into actionable steps to restore and maintain strong email deliverability.
Clean Your Email Lists Regularly
Keeping your email lists clean is key to ensuring high deliverability. Over time, email databases naturally decay - by as much as 22–30% annually. This means regular maintenance is essential to retain strong engagement rates.
Start by removing hard bounces and invalid email addresses, which can account for up to 15% of your list. Next, tackle inactive subscribers - those who haven’t opened or engaged with your emails in the past 90–180 days. Before removing them, consider running a re-engagement campaign, such as sending a "We miss you" email, to see if they’re still interested.
"A smaller, engaged list will outperform a larger, unengaged one every time." – Chris Reed, Executive Director of Marketing, Protect Line
Set up a double opt-in process for new subscribers to confirm email validity and reduce spam traps and fake signups. Additionally, establish a sunset policy for inactive subscribers - typically those who haven’t engaged in 90–180 days. Even a single spam complaint per 1,000 emails can harm your sender reputation.
For most email programs, aim to clean your list every six months. If you manage over 100,000 subscribers, consider doing it every three months. Also, remove role-based accounts like support@, info@, or sales@, as these are often linked to higher spam complaint rates.
Once your list is in good shape, the next step is to ensure your emails are authenticated.
Set Up Email Authentication Correctly
Email authentication is a must for proving the legitimacy of your emails. It helps prevent spoofing and boosts deliverability by signaling to receiving servers that your emails are trustworthy.
Start by setting up an SPF record in your DNS. This record specifies which IP addresses are authorized to send emails on behalf of your domain. For example, a basic SPF record might look like this: v=spf1 include:_spf.google.com ~all.
Next, configure DKIM by generating a key pair. Add the public key to your DNS records and ensure your email server signs outgoing messages with the private key. Finally, implement DMARC, which builds on SPF and DKIM by instructing receiving servers on how to handle unauthenticated emails. Begin with a monitoring policy (p=none) and gradually move to stricter policies like quarantine or reject.
Platforms like Mailforge simplify this process by automating the setup for SPF, DKIM, DMARC, and custom domain tracking, saving you hours of manual configuration.
Improve Your Sender Reputation
Think of your sender reputation as your email “credit score.” A strong reputation ensures your emails land in inboxes, not spam folders.
Never use purchased or scraped email lists. These often contain spam traps or unengaged recipients who are more likely to mark your emails as spam. Instead, grow your list organically through valuable content, lead magnets, and genuine opt-ins.
Segment your audience based on engagement levels to better understand subscriber behavior. Send your most engaging content to highly active subscribers first, then gradually include less engaged segments. Tag subscribers by their source to identify which channels drive the most engagement.
Monitor key metrics like complaint rates, bounce rates, and engagement using the reputation dashboards provided by most email platforms. Consistent tracking can help you spot and address issues early.
Test and Optimize Email Content
Your email content plays a major role in deliverability. To avoid spam filters and boost engagement, experiment with A/B testing for subject lines, sender names, and email formats. This will help you identify what resonates best with your audience.
Use spam testing tools - many email platforms have built-in options - to check for issues like excessive capitalization, suspicious links, or problematic phrases. Strive for a balanced text-to-image ratio, as emails overloaded with images and little text often get flagged by spam filters.
Avoid overused trigger words like "FREE", "URGENT", or "ACT NOW" in your subject lines. Instead, focus on delivering meaningful value to your subscribers. Personalize your emails beyond just adding their name - tailor content based on their behavior, preferences, or demographics.
These strategies, paired with a solid infrastructure, will help you optimize your email deliverability.
Use Shared Email Infrastructure with Mailforge
Managing email infrastructure across multiple domains can get complicated. Mailforge simplifies this process with its shared infrastructure, which is designed to ensure high deliverability while reducing the technical burden.
The platform automates DNS setups for SPF, DKIM, and DMARC, minimizing the risk of manual errors. It also offers features like SSL and domain masking for added security and privacy. Bulk DNS updates make it easy to manage hundreds - or even thousands - of domains efficiently.
One standout benefit of Mailforge’s shared model is that it distributes sender reputation across users. This means businesses sending high volumes of emails can avoid the challenges of managing dedicated IP addresses or complex DNS configurations. With Mailforge handling the infrastructure, you can focus on creating impactful email campaigns without the technical headaches.
Ongoing Email Deliverability Management
Maintaining strong email deliverability isn’t something you can fix once and forget. It requires consistent effort and regular upkeep. With major mailbox providers like Google, Yahoo, and Microsoft tightening their rules for bulk email senders, staying on top of your deliverability game has never been more important.
Run Regular Deliverability Audits
Think of audits as your early warning system - they help you spot problems before they escalate. Start by running monthly inbox placement tests to see where your emails are landing: inbox or spam. Keep an eye on weekly metrics like open rates, click-through rates, and unsubscribe rates. If your bounce rate creeps above 2%, take immediate action.
Don’t overlook your authentication records either. DNS records, including SPF, DKIM, and DMARC, can sometimes be corrupted or accidentally removed during website updates. Regularly verify that these records are correctly configured. Also, watch for spikes in complaint rates. Even one complaint per 1,000 emails can harm your sender reputation. If complaints rise, review your recent campaigns to pinpoint what might be causing the issue.
These audits go hand-in-hand with keeping up-to-date on policy changes from Internet Service Providers (ISPs).
Stay Updated on ISP Policy Changes
Email providers are constantly adjusting their policies and spam filters, so what worked a few months ago might not work today. To stay ahead, use tools like Google Postmaster Tools, Microsoft SNDS, Gmail's Compliance Dashboard, and Yahoo's Complaint Feedback Loop (CFL). These resources provide insights into your sender reputation, spam complaints, and authentication status, and they can flag issues like bounce message errors.
Monitor Performance with Testing Tools
Automated tools are a game-changer for keeping tabs on your email performance. They run tests continuously, alerting you to problems in real time. Use pre-send testing tools to scan for spam triggers before sending your emails, and post-send tools to track delivery and engagement metrics.
Set performance benchmarks: aim for delivery rates above 95% and bounce rates below 2%. Platforms like Warmforge can help you stay on track by offering email warm-up services and placement tests. These features ensure your campaigns maintain steady performance.
Lastly, stay vigilant about phishing and email security threats. Cybercriminals are always coming up with new tricks, and ISPs are constantly updating their filters to counteract them. By monitoring your sender reputation with multiple services, you’ll be better equipped to catch and resolve issues as they arise.
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Key Takeaways for Email Deliverability Success
In 2024, a staggering 361 billion emails are expected to be exchanged daily. Yet, only 20–50% of these emails are actually opened. The gap between what’s sent and what’s successfully delivered continues to widen as email filters grow more stringent.
Common Problems and Practical Solutions
Several common issues can derail your email deliverability efforts. Problems like spam traps, failed authentication, and poorly crafted content often lead to bounced emails and reduced engagement. To combat these, regularly clean your email lists and set up proper authentication protocols like SPF, DKIM, and DMARC.
A damaged sender reputation is another frequent culprit. This often stems from poor practices, such as sending emails to cold lists or ignoring engagement metrics. Many marketers face blacklisting as a result. To build and maintain a strong reputation, start with gradual IP warming, use tools like Google Postmaster and Microsoft SNDS for monitoring, and stick to consistent sending patterns.
Email content and infrastructure also play a major role. Spam-triggering words, overly promotional language, or shared hosting with unreliable senders can cause your emails to be filtered out. Testing your email content before sending and investing in reliable infrastructure can help you avoid these pitfalls.
By addressing these issues, you can take meaningful steps to improve your email deliverability rates.
Next Steps to Improve Deliverability
To tackle these challenges head-on, start by auditing your email setup. Verify your authentication records, check for blacklists using tools like MXToolbox, and analyze your bounce and complaint rates. If your performance is lagging, clean up your email lists and fine-tune your content immediately.
For larger-scale email campaigns, consider using shared infrastructure tools like Mailforge. These platforms offer pre-configured domains and automated authentication, making it easier to warm up new domains and streamline your outreach efforts.
FAQs
What are spam traps, and how can I avoid them to maintain a good sender reputation?
Spam traps are special email addresses set up by internet service providers (ISPs) or anti-spam organizations to catch senders who aren't following best email practices. Hitting one of these traps can damage your sender reputation and hurt your email deliverability.
To steer clear of spam traps, make it a habit to clean your email list regularly and rely on email verification tools to flag invalid or suspicious addresses. Using a double opt-in process is another smart move - it ensures only genuinely interested recipients make it onto your list. Stay away from sending emails to role-based addresses like info@ or admin@, as these are often linked to spam traps. Keep an eye on your engagement metrics to spot and address inactive subscribers. Finally, removing unengaged contacts and following anti-spam laws are essential steps to safeguard your reputation and keep your emails landing where they should.
What’s the difference between SPF, DKIM, and DMARC, and how do they work together to improve email deliverability?
SPF, DKIM, and DMARC: The Essentials of Email Authentication
SPF, DKIM, and DMARC are three powerful protocols designed to improve email deliverability and safeguard against spam and phishing attempts. Here's a quick breakdown of how they work:
- SPF (Sender Policy Framework): This protocol ensures that only authorized servers can send emails on behalf of your domain. It does this by verifying the sender's IP address against a list of approved servers for that domain.
- DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails. This signature acts as proof that the message hasn’t been tampered with during transit and confirms the sender’s identity.
- DMARC (Domain-based Message Authentication, Reporting, and Conformance): Building on SPF and DKIM, DMARC provides instructions for email servers on how to handle unauthorized messages. It also ensures the domain in the "From" header aligns with the authenticated source, adding an extra layer of security.
Together, these protocols form a robust defense for email authentication. They not only help ensure your legitimate emails land in inboxes but also significantly reduce the chances of spam and spoofing attacks.
How often should I audit email deliverability, and what metrics are most important to track for successful campaigns?
To keep your email campaigns running smoothly, it's wise to conduct deliverability audits every quarter. If your business sends a large volume of emails, stepping up to monthly audits can help you catch and address issues before they escalate.
When performing an audit, pay close attention to these key metrics:
- Delivery rate: Aim for a range of 90-98% to ensure most emails reach your audience.
- Bounce rate: Keep this below 3% to protect your sender reputation.
- Spam complaint rate: Stay under 0.08% to maintain credibility with email providers.
- Open rate: A clear measure of how engaged your recipients are.
- Sender reputation: This is closely monitored by email providers and directly impacts whether your emails land in inboxes or spam folders.
By keeping tabs on these metrics, you can quickly spot and fix any problems, ensuring your campaigns stay effective. For businesses expanding their email outreach, tools like Mailforge offer a convenient way to manage domains and mailboxes while maintaining top-tier deliverability.