What is email warming and why it matters for ecommerce
Email warming up VS Bulk sending
Email warming is the gradual process of increasing your email send volume from a new domain to build trust with inbox providers. It’s not just a best practice. It’s a necessity if you want to reach your customers’ inboxes consistently.
Jumping from zero to tens of thousands of emails without warming sends a red flag to Gmail, Outlook, and Yahoo. They assume you’re a spammer, and your emails may get blocked or sent to the junk folder.
Email Marketing Pro tip: Start small, even if your list is big. Prioritize sending to your most engaged subscribers first and scale volume over 2 to 4 weeks.
Why sender reputation takes time to build
Email platforms treat new senders with caution. They want to see consistent, trustworthy behavior before letting your emails land in the primary inbox.
Building a strong reputation means:
- Gaining trust by sending valuable content
- Minimizing bounce and complaint rates
- Encouraging positive signals like opens and clicks
Key idea: Think of it like building credit—you can’t start with a perfect score. You need time and good behavior to prove reliability.
What sender reputation is and how it’s measured
Your sender reputation is like your email credibility score. Internet Service Providers (ISPs) evaluate how trustworthy your domain is before deciding where your email goes. Inbox or spam.
Here’s what ISPs monitor:
- Open and click-through rates
- Bounce and unsubscribe rates
- Spam complaints and trap hits
- Frequency and send volume changes
Reputation impact chart:
| Factor | Impact |
|---|---|
| High open rates | ✅ Positive |
| Low engagement | 🚫 Negative |
| High bounce rates | 🚫 Negative |
| Sudden volume spikes | 🚫 Red flag |
| Spam complaints | 🚨 Immediate damage |
Email Marketing Pro tip: Avoid emailing cold or outdated contacts during warming. Focus on engaged users to create strong, positive signals early on.
When and why you need to warm up an email domain
Warming is essential in the following scenarios:
Launching a new brand or store
Every new domain starts with zero credibility. Warming up early avoids getting filtered by default.
Switching ESPs or domains
Your domain reputation doesn’t transfer to a new ESP or subdomain. You’ll need to rebuild your credibility.
Recovering from spam issues
If your deliverability has dropped or you’ve been blacklisted, warming helps re-establish trust.
Real-world advice: Anytime your email sending infrastructure changes, warming should be part of your checklist.
Step-by-step guide to warming up your email domain
Step 1: Set up SPF, DKIM, and DMARC
These DNS records prove you’re a legitimate sender. Without them, many ISPs will flag or reject your messages.
Do this before sending anything.
Step 2: Start with transactional emails
Use order confirmations and shipping updates. They tend to have high open rates and minimal complaints.
Why this helps: These emails build engagement metrics without sounding salesy.
Step 3: Send only to your most engaged users
Start with subscribers who opened or clicked within the last 30 days. These are your email warm-up champions.
Avoid cold lists. They’re more likely to cause bounces or spam reports.
Step 4: Gradually increase daily volume
| Week | Daily Sends | Weekly Total |
|---|---|---|
| 1 | 100–300 | 1,000–2,000 |
| 2 | 500–1,000 | 3,500–5,000 |
| 3 | 2,000+ | Up to 10,000 |
| 4 | Full Sends | Based on engagement |
Email Marketing Pro Tip: If metrics dip (open rate < 20%, complaint rate > 0.1%), pause and reassess.
Step 5: Monitor your metrics closely
Track open rates, spam reports, and bounce rates every day. If anything spikes, slow down or pause the campaign.
Minimum benchmarks to aim for:
- Open rate: 20%+
- Bounce rate: <2%
- Complaint rate: <0.1%
How to maintain a strong sender reputation after warming
Validate and clean your list regularly
Remove inactive, bounced, or unverified addresses. Use email verification tools and suppression lists.
Why this matters: Sending to dead emails hurts your score, even months after warming.
Segment based on engagement
Send more frequently to:
- People who clicked recently
- Active customers
- Users engaged in the past 60 days
Suppress or clean cold contacts.
Avoid inconsistent sending behavior
Sending once a month in large batches can trigger suspicion. Instead, email smaller segments regularly.
Strategy tip: Establish a predictable rhythm that inbox providers can trust.
Tools that help you monitor and improve sender reputation
| Tool | What It Does |
|---|---|
| Google Postmaster Tools | See Gmail-specific sender metrics |
| GlockApps | Check inbox placement and test across providers |
| Mail-Tester | Analyze spam score and email quality |
| MxToolbox | DNS and blacklist checking |
| WarmUp Inbox / Mailreach | Automate the entire warming process |
Email Marketing Pro tip: Set alerts for major metric drops or deliverability issues using these tools.
Email warming and sender health FAQs
How long does warming up take?
Usually 2 to 4 weeks. Larger lists or poor engagement may require more time.
What happens if I send too much too fast?
You risk spam filters, domain throttling, or even blacklisting.
Do I need to warm up before every campaign?
No. Only when you’re using a new domain, IP, or reactivating a cold list.
Can I automate the warm-up process?
Yes. Tools like Mailreach and WarmUp Inbox simplify it by pacing your sends.
Does a shared ESP protect my domain reputation?
Only partially. For more control and reliability, use a dedicated domain or IP.
Send smarter to grow faster
Email warming is not just technical housekeeping. It’s foundational to your deliverability and long-term success. A well-warmed email domain leads to:
- Better inbox placement
- Higher open and click rates
- More consistent revenue from email
At The Mail Effect, we guide ecommerce brands through smart warm-up strategies that protect your domain, optimize your sending reputation, and maximize your ROI.
