How to Recover from a Sudden Deliverability Drop

For startups and sales teams, email is more than a communication tool; it’s the backbone of lead generation, nurturing, and closing deals. When your outbound campaigns suddenly start landing in spam, or your open rates plummet overnight, it’s not just frustrating; it’s a direct threat to your pipeline and revenue. A sudden drop in email deliverability can derail your outreach strategy, waste marketing spend, and damage your sender reputation.
The good news? Most deliverability issues are fixable if you act quickly and methodically. In this guide, you’ll learn how to diagnose the root cause of a deliverability drop, restore your sender reputation, and implement best practices to prevent future issues. Whether you’re managing cold outreach at scale or running targeted campaigns, these steps will help you get back on track and stay there.

1. Identify the Symptoms

The first step to recovery is recognizing the warning signs. Many teams miss early red flags, making the problem worse. Watch for:

• Sudden drop in open rates: If open rates fall significantly compared to previous campaigns, your emails may not be reaching inboxes.
• Increase in bounce rates: A spike in hard or soft bounces can signal issues with your sending domain, authentication, or list hygiene.
• Higher spam complaints: If recipients mark your emails as spam, mailbox providers may filter all your messages to junk.
• Emails landing in promotions or spam folders: Even delivered emails can have low engagement if they end up in the wrong folder.
• Decline in click-through rates: Lower clicks may be a secondary effect of poor inbox placement.

Pro Tip: Monitor these metrics daily using your email platform or a dedicated deliverability tool. Set up alerts for sudden changes so you can act immediately.

2. Diagnose the Root Cause

Once you’ve confirmed a deliverability drop, it’s time to investigate why. Here’s a systematic approach:

a. Review Recent Campaign Changes

• New lists or segments: Did you upload a new contact list? Purchased or scraped lists often contain invalid or unengaged emails that hurt deliverability.
• Template changes: New subject lines, content, or links can trigger spam filters.
• Sending volume: Rapidly increasing your sending volume or frequency can look suspicious to mailbox providers.

b. Analyze Bounce and Complaint Data

• Hard bounces: Indicate invalid addresses. Too many can get your domain or IP blacklisted.
• Soft bounces: Temporary issues (like full inboxes) are less severe, but a sudden increase may point to broader problems.
• Spam complaints: Track complaint rates. Exceeding thresholds set by providers (e.g., Gmail, Outlook) can result in automatic filtering.

c. Check Blacklists and Sender Reputation

• Use tools like MXToolbox or SenderScore to see if your domain or sending IP is on a blacklist.
• If you’re using a shared IP (common for startups), other senders’ behavior can impact your reputation.

d. Inspect DNS and Authentication Records

• SPF, DKIM, and DMARC: Authentication protocols prove your emails are legitimate. Missing or misconfigured records are a common cause of deliverability issues.
• DNS health: Ensure your sending domains are properly set up, with no expired or conflicting records.

Checklist:

• Did you change anything about your list, content, or schedule?
• Are your bounce and complaint rates above normal?
• Are you on any blacklists?
• Are your SPF, DKIM, and DMARC records valid?

3. Pause and Assess

When you spot a deliverability problem, resist the urge to keep sending. Instead:

• Pause outbound campaigns: Stop sending until you know what’s wrong. Continuing can worsen your reputation and make recovery harder.
• Notify stakeholders: Let your team and management know there’s an issue. Transparency ensures everyone is aligned and avoids duplicate troubleshooting.
• Document recent changes: Record all recent adjustments for easier troubleshooting, changes to domains, templates, lists, and schedules.

4. Restore Technical Health

With sending paused, address technical issues methodically:

a. Fix DNS and Authentication

• SPF, DKIM, and DMARC: Double-check that all records are valid, aligned, and up-to-date. Use online tools to verify each record.
• Domain reputation: If your domain is on a blacklist, follow the removal process outlined by the listing authority.

b. Remove Problematic Contacts

• Clean your lists: Remove hard bounces, spam traps, and unengaged addresses. Use a list cleaning service if needed.
• Segment by engagement: Focus on recipients who have opened or clicked in the past 30–90 days.

c. Warm Up Inboxes

• Gradual ramp-up: If you’re using new domains or IPs, start with small batches and gradually increase volume. Sudden spikes can trigger spam filters.
• Engagement-based sending: Begin with your most engaged recipients to rebuild positive signals.

d. Rotate Sending Domains

• Backups: If one domain is heavily penalized, consider switching to a backup (with proper warm-up). Never send high volumes from a brand-new domain.

e. Check Content

• Spam triggers: Avoid spammy language, too many links, or large attachments.
• Personalization: Use first names, company names, or other custom fields to increase engagement and reduce complaints.

Tip: Test your emails using tools like Mail-Tester or GlockApps to see how they perform against spam filters before resuming full campaigns.

5. Rebuild Sender Reputation

After fixing technical issues, focus on rebuilding trust with mailbox providers:

• Resume with low volumes: Start small with your most engaged audience. Sending too many emails too soon can undo your hard work.
• Monitor metrics: Watch open rates, bounces, and complaints closely. Set benchmarks for each and pause again if metrics deteriorate.
• Gradually scale: Increase sending volume as metrics improve. A typical ramp-up might look like 50 emails/day, then 100, 200, and so on.
• Engagement first: Prioritize recipients who regularly open and click your emails. High engagement signals to providers that your emails are wanted.
• Stay consistent: Maintain a steady schedule and avoid sudden spikes. Consistency is key to long-term deliverability.

6. Prevent Future Drops

Adopt these best practices to ensure long-term deliverability health:

a. Deliverability Monitoring

• Use tools to track inbox placement, blacklist status, and sender reputation. Set up automated alerts for any changes.

b. List Hygiene

• Regularly remove unengaged or invalid contacts. Run list cleaning at least quarterly, or after every major campaign.

c. Best Practices for Cold Outreach

• Personalize: Tailor messages to each recipient and avoid generic templates.
• Avoid spam triggers: Steer clear of all-caps, excessive punctuation, and aggressive sales language.
• Respect opt-outs: Make it easy for recipients to unsubscribe and honor requests promptly.

d. Test Before Sending

• Use inbox placement tests before major sends to catch issues early.
• A/B test subject lines and content to find what works best for your audience.

e. Educate Your Team

• Make deliverability a shared responsibility. Train your team on best practices and keep everyone informed of changes to processes or tools.

FAQs: Troubleshooting Common Deliverability Issues

Q: How long does it take to recover from a deliverability drop?
A: Recovery time depends on the severity and cause. Minor issues can be fixed in days; major reputation damage may take several weeks.

Q: Can I use the same domain after a drop?
A: Yes, but only after cleaning up technical issues and reputation. For severe cases, consider rotating domains and warming up new ones.

Q: What’s the ideal sending volume when restarting?
A: Start with your most engaged segment at low volumes (e.g., 50–100 emails/day) and increase gradually as metrics improve.

Q: What are the most common technical mistakes that cause deliverability drops?
A: Missing or misconfigured SPF/DKIM/DMARC records, sending from new domains without warm-up, and using purchased or poor-quality lists.

Q: How often should I clean my email list?
A: At least every quarter, or before any major campaign. More frequent cleaning is recommended for high-volume senders.

Conclusion

A sudden deliverability drop is stressful, but with a structured approach, you can recover quickly and come back stronger. Diagnose the issue, fix technical problems, rebuild your sender reputation, and implement proactive measures to keep your campaigns healthy.
Ready to take your email deliverability to the next level? Book a demo with Mailpool and discover how we help startups and sales teams maximize inbox placement and ROI.