Email marketing is one of the most powerful tools in your marketing strategy—until it isn’t.
If your emails aren’t reaching inboxes, your engagement rates are plummeting, or your domain reputation is suffering, you may have a deliverability problem.
Many marketers assume that once they hit “send,” their emails automatically reach their subscribers, but email deliverability is far more complex.
Poor email deliverability can mean your emails land in promotion tabs & spam folders, get blocked by email service providers (ESPs) & internet service providers (ISPs), or don’t reach recipients at all. If you rely on email campaigns for engagement, sales, or customer communication, monitoring and optimizing your deliverability health is critical.
Review these seven signs you need an email deliverability health check and what you can do to fix them:
1. Your Bounce Rate Is Rising
A high bounce rate (above 2%) is a red flag that your email list contains outdated, invalid, or fake email addresses. Hard bounces occur when an email is permanently rejected from invalid addresses, while soft bounces happen due to temporary issues—full inboxes or server problems.
If your bounce rate continues rising (above 5%), your sender reputation is at risk, and ESPs may flag you as a spammer. Regular list cleaning and email validation tools can help mitigate this issue.
2. Your Open Rates Are Declining
If your open rates are steadily decreasing, it could be any number of issues.
Your subject lines might not be engaging. Improve your subject lines by making them relevant and personalized.
Your emails could be landing in spam folders & promotion tabs, or your recipients may not recognize your sender name. To address these issues:
- Ensure your sender name and address are recognizable.
- Authenticate your emails using SPF, DKIM, and DMARC to prevent spoofing and maintain email integrity. Without these, ESPs may not trust your emails.
- Use email marketing deliverability enhancement tools to track inbox placement, spam complaints, and bounce rates.
- To go a step further, consider implementing Brand Indicators for Message Identification (BIMI).
What’s BIMI and How Does It Help Email Deliverability?
BIMI allows you to display your brand’s logo next to your sender name in the inbox—giving your emails a visual layer of legitimacy and helping recipients immediately recognize your brand.
This extra level of authentication not only builds brand trust but can also improve open rates by making your messages stand out visually in crowded inboxes.
3. Your Emails Are Landing in Spam Folders
When emails don’t reach the inbox, your sender reputation suffers. Common reasons include:
- Using spam-trigger words (e.g., “Free,” “Buy Now,” “Act Fast”). Avoid the complete list of spam triggers.
- Sending image-only emails with little text. Prevent this by maintaining a healthy text-to-image ratio, something like 60% text to 40% images.
- Failing to comply with email authentication standards. You can encourage recipients to whitelist your email address and always test your emails using email deliverability tools for marketers before sending.
4. You Have High Unsubscribe or Complaint Rates
If too many people unsubscribe or mark your emails as spam, ISPs will start filtering your messages.
Mitigate this by segmenting your list to tailor content to different subscribers so you’re sending relevant and valuable content.
Are you sending 5,000 emails one week and 50,000 the next? Avoid inconsistent sending practices and email fatigue by optimizing your send frequency. Inconsistent sending behavior signals spam-like activity to ISPs.
Gradually warm up new IP addresses and domains, and stick to a consistent email schedule.
But What If I Break From My Schedule?
You send one email most days, and then suddenly want to send three on one specific day? Don’t sweat it. Just make sure it’s value-adding content for your subscribers, and you’ll be fine. It’s those frequent, significant changes that will increase spam filtering risks.
5. Your Emails Have Poor Engagement
Low click-through rates (CTR) or reply rates signal that recipients aren’t finding your emails valuable.
To boost engagement, use personalized email content—A/B test different email formats to see what resonates best. And make sure your calls to action (CTAs) are clear, concise, and compelling. Don’t know where to start? Check out my CTA crafting tips here.
6. Your Sender Reputation Is Suffering, or You’ve Been Blacklisted
Your sender score influences whether inbox providers trust your emails. A low score can lead to your emails being flagged as spam, blocked, or even blacklisted.
- Avoid buying email lists, which often contain spam traps and low-quality contacts.
- Use a dedicated IP address to isolate your reputation from other senders.
- Maintain consistent sending volume and frequency to build credibility with ISPs.
- Regularly monitor your sender score and check your blacklist status using deliverability tools.
7. Your Email List Isn’t Maintained
A healthy email list is the foundation of good deliverability. If you’re not regularly cleaning your list, it could be filled with inactive, fake, or invalid addresses, which can hurt engagement.
You can use email list hygiene tools to routinely remove invalid, duplicate, or fake email addresses.
Take care to eliminate hard bounces, unengaged subscribers, and known spam traps.
Ask new subscribers to reply to your welcome email to validate interest and improve list quality.
Don’t Ignore the Warning Signs
If your email metrics are slipping and your sender reputation is on shaky ground, it’s time to stop guessing and start diagnosing. Your email deliverability health isn’t something to monitor occasionally—it’s something you need to actively manage if you want your messages to land where they belong: in the primary inbox.
You’ve seen the signs—rising bounce rates, declining open rates, spam folder placements, and blacklists are all symptoms of deeper issues.
The good news? Every single one of them is fixable.
Whether it’s authenticating your emails properly, implementing BIMI for visual brand trust, cleaning up your list, or using dedicated tools to track your sender reputation, small adjustments can lead to big deliverability gains.
Remember, email marketing only works if your audience actually sees your emails. So treat your email deliverability like the critical marketing channel it is—invest in the right practices, stay consistent, and get proactive about testing.
Ready to take action? Run a free email deliverability test with MailGenius today and find out exactly what’s standing between your emails and the inbox. When your emails show up in inboxes reliably, your ROI isn’t just preserved—it grows.