So, you got yourself a brand new email domain or SMTP server, and you’re excited to start sending out email campaigns. You’ve written killer content, maybe even designed a cool newsletter. You hit send...
And then... crickets.
Or worse—your emails land in spam. No clicks. No opens. Just wasted effort.
Welcome to the world of email deliverability. And if you’re new here, let me tell you the first hard truth:
You can’t just start blasting thousands of emails from a fresh server or domain.
If you do, you’ll get flagged as spam faster than you can hit "resend."
The solution? You need to warm up your email server the right way.
What Is Email Warm-Up?
Email warm-up is the gradual process of building trust with inbox providers like Gmail, Yahoo, Outlook, and others by slowly increasing the number of emails you send from a new IP address or domain.
When you warm up, you're saying to email systems:
"Hey, I’m a good sender. I’m not here to spam anyone. Look, people are opening and engaging with my messages.”
It’s like building your credit score from scratch. You can’t get a loan on day one—but if you show responsible behavior, your reputation improves over time.
SMTPWire offers warm-up automation built right into their SMTP platform, so you don’t have to manage the process manually or guess how much to send each day.
Why Warming Up Matters More in 2025
Inbox providers are using AI-powered filters, engagement tracking, and advanced sender reputation scoring. They’re constantly evolving, and getting smarter every year.
That means:
Sending too much too soon gets flagged
Low engagement leads to poor sender scores
Spam complaints can tank your domain reputation
In 2025, email warm-up is no longer a “best practice”—it’s essential.
When Do You Need to Warm Up Your Email?
You should warm up if:
You just bought a new domain or subdomain for email
You’re using a new SMTP server or dedicated IP
You haven’t sent emails in a long time
You’re launching cold outreach campaigns
You’re switching providers (like moving to SMTPWire from another platform)
Each of these scenarios signals “new activity” to inbox filters, so you’ll want to proceed carefully.
Step-by-Step: How to Warm Up Your Email the Right Way
Here’s a real-world warm-up strategy that works. If you’re using SMTPWire’s dedicated SMTP server, many of these steps are automated for you. But it’s still good to understand what’s happening behind the scenes.
Week 1
Send 20–50 emails per day to highly engaged, known recipients.
This could be team members, past clients, or friends who will open, click, and reply.
Week 2
Increase to 100–200 emails per day.
Still focus on your most active list segments. Avoid cold contacts.
Week 3
Send 300–500 emails/day.
Start introducing newsletters or soft promotional content. Watch your open rates.
Week 4
Scale to 1,000+ emails/day (or more, depending on your list).
Now you're ready to send full campaigns to your wider audience.
During this entire process, track:
Open rates
Bounce rates
Spam complaints
Click-throughs
The key is slow, steady, and clean. And never add new domains or IPs mid-campaign.
Tools That Make Warm-Up Easier
Doing this manually can be frustrating and time-consuming. You’ll have to build schedules, write custom follow-up content, manage different recipient segments, and keep checking metrics daily.
SMTPWire offers automated warm-up tools that do all of this for you.
You just:
Set up your SMTP server
Connect your email list or CRM
Select warm-up mode
Watch your reputation grow safely
Other Things to Keep in Mind While Warming Up
- Use Email Authentication Make sure SPF, DKIM, and DMARC records are set up correctly for your domain. This is non-negotiable.
SMTPWire’s setup system helps you authenticate your domain without needing a tech expert.
- Avoid Spam Triggers Stay away from overly promotional language in the beginning:
Don’t use ALL CAPS
Avoid too many exclamation marks
Stay clear of “FREE!!!” or “BUY NOW” phrases
Use friendly, conversational language. Think of your email like a personal note, not an ad.
Include Clear Unsubscribe Links
It sounds counterintuitive, but giving people a way out builds trust with inbox filters. If there’s no unsubscribe option, you’ll get flagged fast.Clean Your List
Bad emails = bounces = red flags. Only send to validated, opted-in addresses during warm-up. You can use SMTPWire’s built-in list hygiene features for this.Test Different Send Times
Part of engagement is about timing. Some subscribers open emails in the morning, others in the evening. Warm-up is a good time to experiment.
What Happens If You Don’t Warm Up Properly?
Skipping the warm-up process can have long-term consequences, like:
Your domain getting blacklisted
Your sending IP being blocked by Gmail or Outlook
Your emails going straight to spam—even after warm-up later
Your email provider suspending your account
Basically, rushing into sending 10,000 emails too fast could burn your domain for months (or permanently).
That’s why warm-up isn’t just a nice idea—it’s your insurance policy.
FAQ: Email Warm-Up
Q1: How long does warm-up take?
Typically 2 to 4 weeks. It depends on how much you send and how well your emails perform in terms of engagement.
Q2: What if I already have an old domain but haven’t used it in years?
You still need to warm it up. Email filters see it as “cold” and risky. Treat it like a new sender.
Q3: Can I send cold emails during warm-up?
Avoid that. Cold emails have lower open rates and higher risk. Use only warm, engaged contacts until you’ve built some domain trust.
Q4: What are the best types of emails to send during warm-up?
Welcome emails, check-ins, newsletters, or helpful blog content. Keep it conversational and valuable.
Q5: Is manual warm-up better than automated?
Manual gives you control but takes time. Automated warm-up (like with SMTPWire) is faster, consistent, and includes built-in reputation tracking.
Final Thoughts
Warming up your email server might seem like a technical chore—but it’s one of the smartest things you can do to protect your sender reputation and actually reach the inbox.
In 2025, inbox filters are more advanced than ever. They can detect lazy sending habits, bad content, and unprepared servers instantly.
So why risk it?
Start with a proper SMTP server like SMTPWire.
Use their automation to build trust.
Send better. Inbox more. Stress less.
Because no one wants to waste another campaign that never gets seen.
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