Email warmup is one of the most overlooked yet essential parts of running a successful outbound campaign. Whether you’re launching a cold email strategy or creating new inboxes for your sales team, how you warm up those email accounts can make or break your deliverability.
Done correctly, email warmup helps you avoid spam filters, protect your sender reputation, and ensure your messages actually land in inboxes. Done poorly—or skipped entirely—and your emails may never be seen.
In this guide, we’ll walk through the best practices for email warmup, what tools to use (including Sequence-R’s built-in warmup feature), and how to maintain a healthy sending reputation long term.
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What Is Email Warmup?
Email warmup is the process of slowly and strategically increasing the number of emails sent from a new or inactive email address. The goal is to build trust with email service providers (like Gmail or Outlook) by simulating healthy, human-like sending behavior.
When you begin sending cold emails from a new domain or a fresh inbox, providers treat you with caution. They’re looking for signs that you’re either a legitimate sender—or a spammer. By warming up properly, you prove that your emails are safe and welcomed.
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Who Needs to Warm Up an Email?
Email warmup is essential if:
• You’ve just registered a new domain or email address
• Your inbox hasn’t been used for more than 30 days
• You’re setting up multiple inboxes for outbound campaigns
• You’ve switched to a new email service provider (ESP)
• Your emails are landing in spam folders or experiencing low open rates
Even if your domain is years old, if you’re starting new cold outreach activity, warmup is necessary.
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Step 1: Set Up Your Email Infrastructure
Before you send a single message, make sure your technical setup is correct. This is a foundational step that many skip.
Key DNS Records to Configure:
• SPF (Sender Policy Framework): Identifies the mail servers allowed to send on behalf of your domain
• DKIM (DomainKeys Identified Mail): Ensures message integrity
• DMARC (Domain-based Message Authentication Reporting and Conformance): Prevents spoofing and gives reporting insights
• Custom tracking domain (if using a link tracker)
• Reverse DNS and PTR records
Use tools like MXToolbox or Google Admin Toolbox to test your configuration. If any of these records are missing or misconfigured, your emails are more likely to be flagged as suspicious.
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Step 2: Use a Reliable Warmup Tool
Automated warmup tools help simulate engagement by sending emails between verified inboxes that open, reply, and remove messages from spam. This interaction tells mail providers that you’re a safe sender.
Some of the most popular tools include:
• Sequence-R – A built-in warmup tool designed specifically for cold email campaigns, with customizable volume, reply patterns, and engagement timing
• Mailreach
• Warmup Inbox
• Warmbox
• Folderly
When choosing a tool, look for one that offers warmup networks (not just scheduled sends), auto-replies, and gradual ramp-up controls. With Sequence-R, you can activate warmup for each inbox and monitor daily performance within the platform.
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Step 3: Start Slowly and Stay Consistent
The most common mistake is sending too many emails too fast. That’s a red flag for email providers and will likely land your messages in spam.
Instead, follow a slow, controlled approach. Here’s a more realistic schedule:
Sample Warmup Schedule (Per Inbox):
| Day | Emails Sent |
| 1–3 | 5–10 per day |
| 4–6 | 10–15 per day |
| 7–10 | 20–30 per day |
| 11–14 | 30–40 per day |
| 15+ | Maintain 40–50 per day (if doing cold outreach) |
Keep each inbox below 50 cold emails per day to reduce risk. If you need to scale higher, add more inboxes and stagger your campaigns across them.
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Step 4: Focus on Positive Engagement
Warmup emails need to look natural. The more engagement you generate, the more trust you build.
During the warmup period:
• Send real emails to colleagues or friends and ask them to reply
• Use your warmup tool to automate positive actions (opens, replies, “not spam” marks)
• Avoid adding links, images, or attachments in the beginning
• Keep subject lines and content plain, short, and conversational
You want your sending behaviour to look like that of a real person—not an automated system.
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Step 5: Use a Separate Domain for Cold Email
To protect your brand, don’t use your primary domain for outreach. Instead, set up a similar-looking domain or subdomain specifically for outbound campaigns.
For example:
• Primary domain: yourcompany.com
• Outreach domain: yourcompanymail.com or yourcompanyhq.com
Make sure you configure SPF, DKIM, and DMARC for this new domain too, and treat it like any new sender identity—it needs to be warmed up from scratch.
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Step 6: Keep Your Lists Clean
While this isn’t part of warmup directly, it’s critical for deliverability.
Never send cold emails to unverified addresses. Use a service like NeverBounce, ZeroBounce, or BriteVerify to clean your lists before sending.
A high bounce rate can destroy your sender reputation—even if you’ve warmed up perfectly.
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Step 7: Avoid These Common Mistakes
Here are the most frequent warmup errors to avoid:
• Skipping DNS records or misconfiguring them
• Scaling too fast in the first two weeks
• Using images or links too early
• Sending the same message repeatedly to multiple addresses
• Relying only on automation with zero manual interaction
• Sending too many cold emails from one account
Stick to your warmup schedule, diversify your outreach, and prioritize engagement.
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Step 8: Monitor Deliverability
You can’t improve what you don’t track. Use tools like:
• GlockApps – for inbox placement tests
• Google Postmaster Tools – to monitor domain reputation (for Gmail)
• MXToolbox – to check if you’ve landed on a blacklist
Most warmup tools, including Sequence-R, will also give daily reports showing deliverability health, spam placement, and engagement trends.
If you notice issues, pause campaigns, adjust sending patterns, and review your content for possible spam triggers.
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Step 9: Maintain Ongoing Warmup Activity
Even after the initial warmup, it’s important to keep your inboxes active.
A few recommendations:
• Keep the warmup tool running in the background (at a lower rate)
• Maintain some manual replies from real users
• Rotate inboxes to avoid overuse
• If you take a break for a few weeks, rewarm the inbox slowly before resuming campaigns
Think of it like keeping your email engine idling—even when you’re not driving it full-speed.
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Final Thoughts
Warming up your email accounts is no longer optional if you want your outbound messages to land in inboxes. Without it, even the most compelling cold email strategy won’t work.
Start slow. Focus on engagement. Use a trusted warmup tool like Sequence-R. Monitor performance every day. And above all, respect the limits of your inbox—keep cold emails under 50 per day per account and scale only when you’re sure your deliverability is solid.
When done properly, email warmup sets you up for higher open rates, more replies, and a healthier domain reputation over the long term.