This Email Deliverability Case Study begins with a common problem.
Great campaigns. Strong offers. Clean design.
Yet emails were landing in spam.
Open rates were falling. Revenue was shrinking. Marketing efforts were being wasted.
The company was sending over 120,000 emails per month. However, nearly half never reached the inbox.
Here were the numbers:
- Inbox placement rate: 52%
- Open rate: 14%
- Spam rate: 18%
- Bounce rate: 9%
In other words, almost one out of every two emails was invisible.
That changed within eight weeks.
By implementing a structured deliverability strategy using Mailozar, we improved inbox placement by 40%, reduced spam complaints by 60%, and doubled open rates.
This case study explains exactly how we did it — step by step.
The Problem: Poor Deliverability Was Blocking Growth
Before we improved anything, we audited performance.
The findings were clear.
Key Deliverability Metrics (Before)
| Metric | Before |
|---|---|
| Inbox Placement | 52% |
| Open Rate | 14% |
| Spam Rate | 18% |
| Bounce Rate | 9% |
The business assumed the issue was content.
It was not.
The real problem was email infrastructure and sender reputation.
Symptoms We Identified
- Emails frequently landed in Gmail Promotions or Spam
- Campaign performance fluctuated unpredictably
- High soft bounces
- Gradual decline in sender reputation
- Increasing spam complaints
At this stage, sending more emails would only make things worse.
So we looked deeper.
Why Deliverability Was Failing
To improve email deliverability, you must understand why it is failing.
Here were the root causes.
1. Missing Proper Email Authentication
SPF was partially configured.
DKIM was not aligned properly.
DMARC policy was set to “none.”
This tells mailbox providers that the sender cannot fully prove identity.
Without authentication, trust drops.
And when trust drops, emails go to spam.
2. Cold Sending Domain
The domain was only three months old.
No structured email warm-up had been done.
Suddenly sending 20,000 emails per day from a cold domain is a red flag.
Mailbox providers interpret this as suspicious behavior.
3. Sudden Volume Spikes
There was no consistent sending pattern.
Some days: 3,000 emails.
Other days: 25,000 emails.
That volatility damages sender reputation.
Consistency builds trust. Spikes destroy it.
4. Poor List Hygiene
The email list had:
- Old inactive contacts
- Role-based emails
- High bounce risk addresses
- No engagement-based segmentation
As a result:
- Bounce rate increased
- Spam complaints increased
- Engagement dropped
Mailbox providers monitor these signals closely.
5. No Deliverability Monitoring
There was no inbox placement testing.
No spam score analysis.
No sender reputation monitoring.
The team was essentially flying blind.
That is where Mailozar came in.
The Strategy: How Mailozar Helped Improve Email Deliverability
Improving deliverability requires structure.
We implemented a step-by-step framework using Mailozar’s deliverability tools.
Step 1: Full Email Authentication Setup (SPF, DKIM, DMARC)
Authentication is non-negotiable.
Using Mailozar’s guided setup:
✔ SPF was corrected and aligned
✔ DKIM was properly configured
✔ DMARC policy moved from “none” to “quarantine”
✔ Domain alignment issues were fixed
Impact:
- Improved sender trust
- Reduced spoofing risk
- Higher authentication pass rates
- Better inbox credibility
Authentication alone improved inbox placement by 8%.
Step 2: Structured Email Warm-Up
Email warm-up builds reputation gradually.
We reduced sending volume dramatically.
Then increased it slowly over 4 weeks.
Warm-up strategy included:
- Sending to highly engaged users first
- Gradual volume increase (10–15% daily)
- Monitoring engagement signals
- Removing inactive contacts
Mailozar’s warm-up tracking ensured no abnormal spikes.
Impact:
- Sender reputation stabilized
- Spam filtering reduced
- Engagement signals improved
Step 3: List Cleaning & Segmentation
List hygiene directly affects deliverability.
We cleaned the database by:
✔ Removing hard bounces
✔ Suppressing inactive users (90+ days)
✔ Removing role-based emails
✔ Segmenting by engagement level
After cleaning, the list size dropped by 18%.
But performance improved immediately.
Impact:
- Bounce rate reduced from 9% to 3%
- Spam complaints dropped
- Engagement increased
Sending fewer but better emails is always smarter.
Step 4: Spam Score Testing
Before sending campaigns, we tested emails for spam triggers.
Mailozar identified:
- Risky subject line patterns
- Broken links
- Improper HTML formatting
- Image-to-text ratio imbalance
We optimized content accordingly.
Impact:
- Reduced spam flag probability
- Improved Gmail inbox placement
- More consistent performance
Step 5: Inbox Placement Testing
Inbox placement testing showed where emails landed:
- Primary
- Promotions
- Spam
Instead of guessing, we measured.
We adjusted:
- Sending times
- Subject line styles
- Engagement targeting
- Content formatting
This continuous optimization helped increase inbox placement rate significantly.
Step 6: Monitoring Sender Reputation
Deliverability is not a one-time fix.
We continuously monitored:
- Domain reputation
- IP reputation
- Spam complaint rate
- Bounce rate
- Engagement trends
Mailozar’s monitoring dashboard allowed proactive action before damage occurred.
The Results: 40% Deliverability Improvement
After eight weeks, the difference was measurable.
Before vs After Comparison
| Metric | Before | After |
|---|---|---|
| Inbox Placement | 52% | 92% |
| Open Rate | 14% | 28% |
| Spam Rate | 18% | 7% |
| Bounce Rate | 9% | 3% |
| Spam Complaints | Reduced by | 60% |
That is a 40% improvement in deliverability.
But the impact did not stop there.
Revenue Impact
Higher inbox placement means more visibility.
More visibility means more engagement.
Within two months:
- Campaign-driven revenue increased by 34%
- Customer retention improved
- Re-engagement campaigns performed better
- Cost per acquisition dropped
Deliverability is directly linked to revenue.
Why This Email Deliverability Case Study Matters
Many businesses believe their problem is:
- Weak subject lines
- Poor copy
- Low discounts
But often, the real issue is infrastructure.
If emails do not reach the inbox, nothing else matters.
This case study proves that:
- Deliverability is technical and strategic
- Warm-up works when done correctly
- Authentication improves trust
- List hygiene protects reputation
- Monitoring prevents future damage
Deliverability is not luck.
It is a system.
Key Takeaways to Improve Email Deliverability
If you are struggling with spam issues, remember:
1. Authentication Is Non-Negotiable
Set up SPF, DKIM, and DMARC properly.
Without it, inbox placement suffers.
2. Warm-Up Protects Sender Reputation
Never send high volumes from a cold domain.
Build trust gradually.
3. Clean Lists Perform Better
Remove inactive users regularly.
Engagement drives inbox placement.
4. Monitor Continuously
Reputation can decline quickly.
Tracking metrics prevents sudden drops.
5. Deliverability Is Ongoing
It requires maintenance.
Testing.
Optimization.
Consistency.
Who Should Use Mailozar?
This approach works best for:
- Email marketing agencies
- SaaS companies
- eCommerce brands
- D2C businesses
- Startups scaling fast
- Bulk email senders
If you send thousands of emails monthly, deliverability tools are essential.
Mailozar is especially helpful for teams that:
- Face spam placement issues
- Have declining open rates
- Recently changed domains
- Struggle with authentication setup
- Need better inbox visibility
Frequently Asked Questions
- How long does it take to improve email deliverability?
Most improvements appear within 2–6 weeks. Full sender reputation recovery may take 8–12 weeks, depending on damage level.
- What is a good inbox placement rate?
A healthy inbox placement rate is 85% or higher. Top-performing senders achieve 90%+ consistently.
- Does email warm-up really work?
Yes. Gradual warm-up builds trust with mailbox providers. Sudden volume spikes damage reputation.
Conclusion: A 40% Improvement Is Achievable
This Email Deliverability Case Study shows one clear lesson.
If your emails are going to spam, the solution is not sending more emails.
It is fixing the foundation.
With proper authentication, structured warm-up, list cleaning, and continuous monitoring, we improved inbox placement from 52% to 92%.
That is a 40% deliverability increase.
And it is achievable.
If your emails are not reaching the inbox, it is time to fix the root cause — not just increase volume.
Audit your deliverability.
Measure your inbox placement.
And build a system that protects your sender reputation long term.