Email Warm-Up Experiment: Does It Actually Improve Deliverability?
Email deliverability is one of the biggest challenges in email marketing, especially when using a new domain or a new email address. Many marketers recommend warming up an email account before sending campaigns, but does it really work? In this experiment, we tracked real email warm up results to see whether warming up an email account actually improves deliverability.
This experiment was conducted to measure real email warm up results, including inbox placement, open rates, spam rates, and overall email performance. If you are planning to start cold email outreach or email marketing using a new domain, these email warm up results will help you decide whether warming up is worth the time.
What Is Email Warm-Up?
Before we discuss the email warm up results, it is important to understand what email warm-up is. Email warm-up is the process of gradually increasing the number of emails sent from a new email account while building a positive sender reputation.
The goal of email warm-up is to show email providers that your emails are legitimate and that recipients are engaging with your messages. Proper warm-up can improve sender reputation, which leads to better deliverability. The email warm up results in this experiment will show whether this process actually works.
How We Conducted the Experiment
To get accurate email warm up results, we tested two new domains:
- Domain A: Warmed up for 14 days
- Domain B: No warm-up
Both domains sent the same number of emails, used the same email content, and targeted similar recipients. This allowed us to compare the email warm up results fairly.
Metrics We Tracked:
- Inbox placement rate
- Spam folder placement
- Open rate
- Reply rate
- Bounce rate
These metrics helped us measure real email warm up results and compare warmed vs non-warmed domains.
Email Warm Up Results: Week-by-Week Data
Below is a summary of the email warm up results after running the experiment.
| Metric | Warmed Domain | Not Warmed Domain |
| Inbox Placement | 88% | 54% |
| Spam Placement | 6% | 32% |
| Open Rate | 48% | 21% |
| Reply Rate | 12% | 3% |
| Bounce Rate | 2% | 5% |
These email warm up results clearly show that warming up an email domain significantly improves deliverability and engagement.
Key Findings From the Email Warm Up Results
1. Inbox Placement Improved
The most important finding from the email warm up results was inbox placement. The warmed domain had 88% inbox placement, while the non-warmed domain had only 54%.
This means that without warm-up, almost half of the emails went to spam. These email warm up results show that warm-up plays a major role in inbox placement.
2. Spam Rates Were Much Lower
Another major difference in the email warm up results was spam placement. The warmed domain had only 6% spam placement, while the non-warmed domain had 32%.
This is a huge difference and one of the most important email warm up results from this experiment.
3. Open Rates Increased
Because more emails landed in the inbox, open rates were much higher for the warmed domain. The email warm up results showed open rates of 48% for the warmed domain compared to 21% for the non-warmed domain.
This proves that deliverability directly affects engagement, which was clearly visible in the email warm up results.
4. Reply Rates Improved
Reply rates were also significantly higher in the warmed domain. The email warm up results showed a reply rate of 12% compared to only 3% for the non-warmed domain.
This shows that warming up an email account not only improves deliverability but also improves campaign performance.
5. Bounce Rates Were Lower
The email warm up results also showed slightly lower bounce rates for the warmed domain. This is because warmed domains build trust with email providers over time.
Why Email Warm-Up Improves Deliverability
The email warm up results from this experiment confirm that email providers monitor sender behavior. When a new domain suddenly sends many emails, providers may flag it as suspicious. However, when emails are sent gradually and recipients engage with them, sender reputation improves.
This explains why the email warm up results showed better inbox placement and lower spam rates for the warmed domain.
How to Warm Up an Email Domain Properly
Based on the email warm up results, here is a simple warm-up schedule:
| Day | Emails Per Day |
| 1–3 | 5–10 emails |
| 4–7 | 15–20 emails |
| 8–10 | 25–35 emails |
| 11–14 | 40–50 emails |
During warm-up, emails should be opened, replied to, and marked as important. This improves sender reputation and leads to better email warm up results.
Tools Commonly Used for Email Warm-Up
Many businesses use tools to automate warm-up. These tools send emails automatically and simulate engagement, which improves sender reputation and email warm up results over time.
Using warm-up tools can save time and improve consistency, which leads to better email warm up results.
Final Conclusion: Email Warm Up Results
So, does email warm-up actually work? Based on this experiment, the answer is yes. The email warm up results clearly showed improvements in inbox placement, open rates, reply rates, and spam reduction.
If you are starting cold email outreach, launching a new domain, or using a new email account, warming up your email is highly recommended. The email warm up results from this experiment show that skipping warm-up can lead to poor deliverability and low engagement.
The most important takeaway from these email warm up results is that sender reputation matters. Email warm-up helps build that reputation, which leads to better deliverability and better campaign performance.
At Massmailmatters.com, we believe that if you want better email marketing performance, higher inbox placement, and more replies, then improving your email warm up results should be one of your top priorities before launching any email campaign.