When you’re ready to start sending cold outreach emails, it’s tempting to dive right in. But here’s a key insight: if you jump straight into sending hundreds of emails from a brand-new inbox, you’re setting yourself up for trouble.
Instead, you need to “warm up” your inbox first. Warming up is like building a positive reputation with email providers so your messages actually land in inboxes — not spam folders.
This guide will show you why warmup matters, how to do it, and which tools to consider. By the end, you’ll know exactly how to give your inbox the best possible start.
Why Warmup Matters: Think of It Like a Credit Score
Imagine your sender reputation as a credit score — but for email. When you open a brand-new inbox, it’s like getting a new credit card with no credit history. Email providers (like Google or Outlook) don’t know you yet. Are you a trustworthy sender or a spammer?
Positive Interactions Raise Your Score: In the email world, good “credit” comes from recipients opening your messages, replying to them, and not flagging them as spam. Positive engagement (like replies and forwards) tells email providers, “This sender is legit!”
Negative Interactions Lower Your Score: Conversely, if people ignore your messages, mark them as spam, or react negatively, your “credit score” drops. Too many bad signals, and your messages start landing in spam folders.
When you start sending emails from a cold inbox with no history, you’re gambling. One too many ignored or spam-flagged emails, and your reputation tanks right out of the gate. That’s why warmup is critical. It builds a history of positive interactions, gradually increasing your email “credit score” before you send real cold outreach messages.
The Warmup Timeline: 2 Weeks Minimum, 3-4 Weeks Ideal
Warming up your inbox is not an overnight process. Just like establishing good credit, it takes time and consistent positive actions.
Minimum Warmup: 2 weeks
Ideal Warmup: 3-4 weeks
In the first few weeks, you’ll start with a very low sending volume and gradually increase it. By the end of the warmup period, you’ll be sending more emails at a steady pace, and providers will trust you more.
Rushing this process is a common mistake — be patient, and your deliverability will thank you.
Why Keep Warmup Running in the Background?
It might seem like once you’ve finished the initial 2-4 week warmup period, you can stop. But here’s a pro tip: don’t stop warming.
Keep it running in the background as you send cold emails. This ongoing positive activity helps maintain and even improve your “credit score” over time.
Email deliverability isn’t binary — it’s not as if all your emails go straight to spam or straight to the inbox. Instead, it’s a sliding scale. Continuously warming up helps tilt the balance in your favor, ensuring more of your emails reach the inbox.
How to Warm Up Your Inboxes (and Which Tools to Use)
The good news? You don’t have to do this manually. Several tools automate the warmup process by sending test emails to inboxes that are part of a controlled network.
These test emails get opened, replied to, and engaged with positively, boosting your credibility in the eyes of email service providers.
Using Revli’s Built-In Warmup
If you’re already using a dedicated email sequencer tool (like HubSpot or Apollo.io) and you’re only missing the warmup piece, Revli has you covered. Revli’s standalone warmup feature can handle all the heavy lifting of gradually increasing your sending volume.
As Revli focuses on warmup (and not a sequencer), it’s perfect if you’re happy with your existing outreach platform.
All-in-One Warmup & Sequencer Tools: Instantly.ai & Smartlead
If you’re starting from scratch and want both warmup and sequencing in one platform, consider tools like Instantly.ai or Smartlead. These platforms provide warmup features and also let you schedule and send your cold outreach sequences from the same dashboard.
Which Option Should You Choose?
It depends on your setup and goals:
If You Already Have a Sequencer (e.g., HubSpot, Apollo.io): Use Revli’s warmup to build your reputation and keep your existing sequencer for outreach.
If You Need Both Warmup & Sequencing in One Place: Consider Instantly.ai or Smartlead for a combined solution.
Either way, the key is consistency. Warm your inboxes for at least two weeks (ideally three to four), and keep warmup running in the background once you start sending cold emails.
Step-by-Step Warmup Process
With a warmup tool, you don’t need to manually adjust sending volumes daily. Most have pre-set configurations to ramp up email volume gradually.
Connect Your Inbox: Plug in your inbox credentials to the warmup tool. It starts by sending a few emails on Day 1 (e.g., 2 emails), then 4 emails on Day 2, 6 on Day 3, and so forth, until it reaches a steady volume of around 40-50 emails per day over a few weeks.
Add Your Email Signature & Set Your Timezone: Within the warmup tool’s settings, add your email signature for professionalism and set your timezone so emails go out at natural business hours.
Use a Custom Tag & Filter Your Inbox: Warmup emails often include a special tag in the subject line (e.g., “[rwu]”). Create an email filter in your inbox to automatically archive these messages, keeping them out of your main inbox. This way, you can focus on genuine replies from leads.
Automatic Interaction & Incremental Increases: The warmup tool’s network will “open” and “reply” to these emails automatically, boosting your inbox reputation. Over 2-4 weeks, you build a solid track record of positive interactions.
By the end of the warmup period, email providers view your domain and inbox as more trustworthy, making it more likely that your genuine outreach lands in the inbox, not the spam folder.
Ongoing Warmup: Keep the Momentum Going
Once you’ve completed the initial warmup, don’t shut it off. Keep warm up running in the background while you send cold emails. This continuous stream of positive signals helps maintain and improve your deliverability over time.
Common Mistakes to Avoid
Rushing the Process: Don’t skip straight to high-volume sends. Trust the warmup tool’s pacing.
Stopping Warmup: Even after the initial period, keep warmup running for steady positive engagement.
Ignoring Setup Details: Add your signature, set your timezone, and filter out warmup emails so your inbox stays clean.
Key Takeaways
Your Inbox Reputation = Your Email “Credit Score”: Build it gradually with consistent positive interactions.
Warm Up for 2-4 Weeks: Give your inbox time to earn trust before ramping up outreach.
Choose Tools That Fit Your Needs:
Already have a sequencer? Add Revli’s warmup.
Need an all-in-one solution? Consider Instantly.ai or Smartlead.
Keep Warmup Running in the Background: Continuous warmup maintains and improves deliverability over time.
Ready to Get Started?
Don’t gamble with your email deliverability. Start warming up your inbox today.
Whether you choose Revli or an all-in-one tool like Instantly or Smartlead, patience and consistency will pay off with higher open rates, better inbox placement, and more successful outreach campaigns.
👉 Next Step: How to Craft High-Converting Email Copy
Learn how to write subject lines, body copy, and CTAs that get replies and drive results. Elevate your outreach messages and turn leads into loyal customers!