10 Tested Strategies to Solve Your Email Deliverability Problems

Email deliverability is one of the most critical aspects of any digital marketing, sales, or communications strategy. No matter how persuasive your email content is, if your messages never reach the recipient’s inbox, all your efforts are wasted. Poor deliverability can result from spam complaints, incorrect authentication, low engagement, or blacklisting, among other factors. Below, we explore 10 proven strategies to fix and optimize email deliverability.

1. Authenticate Your Emails with SPF, DKIM, and DMARC

Why it matters:
Email providers like Gmail, Outlook, and Yahoo use authentication protocols to verify that the sender is legitimate. Failing to authenticate emails can lead to messages being flagged as spam.

Steps to implement:

SPF (Sender Policy Framework): Publish a DNS record specifying which servers are allowed to send emails on your domain’s behalf.
DKIM (DomainKeys Identified Mail): Sign your emails with a private key that recipients can verify against a public key in your DNS.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): Helps monitor and enforce email authentication policies, telling providers how to handle unauthenticated emails.

Case example:
A SaaS company was experiencing 30% of emails landing in spam. After setting up SPF, DKIM, and DMARC properly, inbox placement improved by over 50%, with Gmail showing a marked reduction in spam labeling.

2. Maintain a Clean and Engaged Email List

Why it matters:
Inactive or incorrect email addresses can result in bounces, which hurt your sender reputation.

Strategies:

Regularly remove bounced, inactive, or unsubscribed addresses.
Use re-engagement campaigns to confirm interest before removing contacts.
Segment based on engagement (opens, clicks) to target only active users.

Case example:
An e-commerce brand noticed that 15% of its list was inactive. After cleaning its list and re-engaging users with a “We miss you” campaign, deliverability rates increased by 20%.

3. Avoid Spam Trigger Words and Overuse of Links

Why it matters:
Spam filters evaluate content. Overly promotional language or excessive links can trigger spam filters.

Tips:

Avoid phrases like “Buy Now,” “Free Money,” “100% Guarantee.”
Limit the number of links; ensure URLs are trustworthy and not blacklisted.
Use plain language and provide value rather than pushing sales aggressively.

Case example:
A marketing agency switched from overly promotional templates to value-driven content. Spam complaints dropped by 40%, improving sender reputation.

4. Monitor Sender Reputation

Why it matters:
Your sender reputation is like a credit score for emails. Low reputation increases the chance of emails being blocked or flagged as spam.

How to monitor:

Use tools like SenderScore, Google Postmaster Tools, or Microsoft SNDS.
Track metrics: bounce rate, spam complaints, unsubscribe rate, and engagement levels.
Maintain a dedicated sending IP if possible to isolate reputation issues.

Case example:
A fintech startup discovered its shared IP had a poor reputation due to another client’s spamming. Moving to a dedicated IP and monitoring reputation improved inbox delivery by 35%.

5. Segment Your Audience

Why it matters:
Sending the same message to your entire list can hurt engagement. Engaged users improve reputation; unengaged users hurt it.

Strategies:

Segment based on demographics, purchase history, or engagement levels.
Tailor content for each segment to maximize opens and clicks.
Re-engage or suppress inactive segments to avoid high bounce rates.

Case example:
A travel company segmented users by recent booking behavior and personalized emails accordingly. Open rates increased from 18% to 32%, directly boosting deliverability.

6. Warm Up New IP Addresses Gradually

Why it matters:
Email providers distrust new IP addresses with sudden high volumes. Sending too many emails too quickly can trigger spam filters.

Steps to warm up:

Start sending a small number of emails daily (e.g., 50–100).
Gradually increase the volume over several weeks.
Monitor engagement metrics to adjust sending pace.

Case example:
A startup launched a new email server and initially sent 50,000 emails daily. Many went to spam. After a 4-week warm-up plan, inbox placement improved from 60% to 92%.

7. Use Double Opt-In for Subscribers

Why it matters:
Double opt-in ensures that users explicitly confirm they want to receive emails. This reduces spam complaints and increases engagement rates.

Implementation:

Upon sign-up, send a confirmation email with a link the subscriber must click.
Only add confirmed users to your main mailing list.
Track opt-in confirmations to maintain a verified subscriber database.

Case example:
A newsletter platform moved from single to double opt-in. Although subscriber numbers were slightly lower, engagement rates jumped 25%, and spam complaints decreased drastically.

8. Monitor and Reduce Bounce Rates

Why it matters:
Hard bounces (invalid addresses) and soft bounces (temporary failures) negatively impact sender reputation.

Solutions:

Remove hard bounces immediately.
Retry soft bounces a few times, but remove persistent failures.
Use list validation tools (e.g., ZeroBounce, NeverBounce) before sending campaigns.

Case example:
An online retailer used a validation service before sending a holiday campaign. Bounce rates dropped from 12% to 2%, improving delivery to Gmail and Yahoo inboxes.

9. Provide an Easy Unsubscribe Option

Why it matters:
Forcing users to remain on your list increases spam complaints. A clear unsubscribe link keeps your list healthy and reduces complaints.

Best practices:

Place the unsubscribe link at the top or bottom of the email.
Allow one-click unsubscribe without login.
Use the feedback loop to understand why users opt out.

Case example:
A B2B company simplified its unsubscribe process. Spam complaints dropped from 0.8% to 0.2%, increasing overall sender trust with ISPs.

10. Regularly Monitor Blacklists

Why it matters:
Being on blacklists (Spamhaus, SORBS, etc.) prevents emails from reaching inboxes.

Steps:

Check blacklist status using tools like MXToolbox.
Identify the cause (e.g., spam complaints, malware) and resolve it.
Request delisting once issues are fixed.

Case example:
A financial services company was blacklisted after a phishing incident from a compromised account. Immediate removal of compromised accounts, combined with ISP communication, restored deliverability in 48 hours.

1. Authenticate Emails with SPF, DKIM, and DMARC

Problem:
A SaaS company found that 30% of their marketing emails were landing in recipients’ spam folders. Their domain was not fully authenticated.

Solution:

Implemented SPF to authorize sending servers.
Set up DKIM to cryptographically sign emails.
Configured DMARC to monitor and enforce authentication policies.

Result:
Inbox placement improved from 70% to 90%. Gmail marked far fewer messages as spam, and overall engagement increased by 25%.

Key takeaway:
Authentication builds trust with email providers, which directly improves deliverability.

2. Maintain a Clean and Engaged Email List

Problem:
An e-commerce brand had a 15% bounce rate, reducing their sender reputation and triggering spam filters.

Solution:

Removed inactive and bounced email addresses.
Ran a re-engagement campaign: “We miss you – click to stay subscribed.”
Segmented subscribers based on recent activity.

Result:
Deliverability rates increased by 20%, and open rates went up from 22% to 29%.

Key takeaway:
Regular list cleaning removes unengaged recipients that can harm your reputation.

3. Avoid Spam Trigger Words and Excessive Links

Problem:
A marketing agency’s emails were flagged as spam despite low bounce rates. They overused promotional words and links.

Solution:

Removed phrases like “Buy Now” and “100% Free.”
Reduced the number of links per email.
Focused on content that educated and engaged recipients.

Result:
Spam complaints dropped by 40%, and click-through rates improved by 18%.

Key takeaway:
Content matters. Emails that are too salesy or overloaded with links are more likely to hit spam.

4. Monitor Sender Reputation

Problem:
A fintech startup shared a sending IP with other companies. One of them was flagged for spam, causing the IP’s reputation to drop.

Solution:

Migrated to a dedicated IP address.
Regularly monitored metrics with SenderScore and Google Postmaster Tools.

Result:
Inbox placement improved from 65% to 90%, and engagement increased significantly.

Key takeaway:
Your IP reputation is critical; monitoring it helps prevent external issues from affecting your campaigns.

5. Segment Your Audience

Problem:
A travel company was sending the same generic newsletter to all subscribers, resulting in low engagement and increased spam complaints.

Solution:

Segmented users by recent travel behavior, location, and engagement history.
Sent personalized offers and content relevant to each segment.

Result:
Open rates increased from 18% to 32%, and spam complaints dropped by 50%.

Key takeaway:
Targeted emails improve engagement, which in turn improves deliverability.

6. Warm Up New IP Addresses Gradually

Problem:
A SaaS startup started sending 50,000 emails/day from a new IP. ISPs flagged many messages as spam.

Solution:

Implemented a 4-week IP warm-up schedule, starting with 100 emails/day.
Gradually increased the volume while monitoring engagement.

Result:
Inbox placement improved from 60% to 92%, and engagement remained steady.

Key takeaway:
Gradual warming avoids sudden spikes that trigger ISP filters.

7. Use Double Opt-In for Subscribers

Problem:
A newsletter platform experienced spam complaints due to invalid or mistyped email addresses from single opt-in.

Solution:

Introduced double opt-in: users had to confirm subscription via a verification email.
Removed unconfirmed addresses from the main list.

Result:
Spam complaints decreased from 0.8% to 0.2%, and engagement rates rose by 25%.

Key takeaway:
Double opt-in ensures a qualified, engaged audience, improving sender reputation.

8. Monitor and Reduce Bounce Rates

Problem:
An online retailer’s holiday campaign saw a 12% bounce rate, harming email deliverability.

Solution:

Validated the email list using NeverBounce.
Removed hard bounces immediately and retried soft bounces.

Result:
Bounce rate fell to 2%, and inbox delivery improved across all major ISPs.

Key takeaway:
Lower bounce rates signal ISPs that your emails are legitimate and wanted.

9. Provide an Easy Unsubscribe Option

Problem:
A B2B company received high spam complaints because subscribers couldn’t easily opt out.

Solution:

Added a prominent one-click unsubscribe link.
Collected feedback on why users opted out.

Result:
Spam complaints dropped from 0.8% to 0.2%, and overall engagement improved.

Key takeaway:
Making unsubscribes easy prevents recipients from marking emails as spam, protecting your reputation.

10. Regularly Monitor Blacklists

Problem:
A financial services company discovered that its emails weren’t reaching inboxes. They were blacklisted due to a compromised account sending phishing emails.

Solution:

Immediately secured compromised accounts.
Checked blacklists using MXToolbox.
Contacted ISPs and requested delisting.

Result:
Deliverability restored within 48 hours, with inbox placement back at 95%.

Key takeaway:
Blacklist monitoring helps catch issues early and quickly restore deliverability.

Conclusion

Email deliverability depends on technical setup, list hygiene, content quality, and sender reputation. These 10 strategies, when implemented systematically, solve most email delivery problems and ensure campaigns reach their audience.

Summary Table:

Strategy	Key Impact	Case Outcome
SPF/DKIM/DMARC	Authentication	Inbox placement +20%
Clean List	Reduced bounces	Deliverability +20%
Avoid Spam Words	Content quality	Spam complaints -40%
Monitor Reputation	IP trust	Inbox placement +25%
Segmentation	Engagement	Open rates +14%
IP Warm-Up	Gradual sending	Inbox placement +32%
Double Opt-In	Verified list	Spam complaints -0.6%
Reduce Bounce	List health	Bounce -10%
Easy Unsubscribe	Reputation	Spam complaints -0.6%
Blacklist Monitoring	ISP trust	Delivery restored in 48h