If you’re launching cold email campaigns, blasting out newsletters, or just setting up a fresh domain, you’ve probably heard about “warming up” your email domain. But what does that actually mean? And is it really worth the effort? If you want your emails to land in the inbox (not the spam folder), warming up your domain isn’t optional—it’s essential. This guide is for anyone who wants a real, step-by-step process using Lemlist to boost deliverability, without wasting time on fluff or hype.
Let’s cut through the noise and get your emails actually seen.
Why Bother Warming Up Your Email Domain?
Before we get to the how-to, let’s be honest: email warming isn’t magic. It’s just about showing mailbox providers (like Gmail or Outlook) that you’re a “good sender.” They don’t know you yet, and if you suddenly show up blasting 500 emails a day, you’ll look like a spammer.
Warming up is about pacing yourself, building a good reputation, and avoiding rookie mistakes that get you blacklisted before you even start.
Who needs to warm up?
- Anyone using a new domain or email address for bulk sending
- Businesses switching email providers
- Cold emailers, B2B sales, or outreach teams
- Newsletter senders who haven’t emailed in a while
Who can skip it?
- Folks sending personal emails to friends and family
- Companies with a long sender history and great engagement
If you’re in the first list, keep reading.
Step 1: Set Up Your Domain & Email Properly
Don’t even think about warming up until your technical foundations are solid. Here’s what matters:
1.1 Set Up Domain Authentication (Absolutely Non-Negotiable)
- SPF: Authorizes which servers can send for your domain
- DKIM: Cryptographic signature proving your email’s legit
- DMARC: Tells inboxes what to do if SPF/DKIM fail
If you skip these, warming up won’t matter. Your emails will go to spam or get blocked outright.
Pro Tip: Use tools like MXToolbox or Google Postmaster Tools to check your records.
1.2 Create a Realistic Sender Address
- Use a real name, not “no-reply@” or “info@.”
- Avoid brand-new domains—Google especially hates these. If possible, let your domain age for a few weeks.
- Fill out your profile: add a signature, profile photo, and “about” info.
1.3 Test Sending Manually First
Send a few real, non-spammy emails to friends, colleagues, or even your own other accounts. Get replies. This helps prime the pump.
Step 2: Connect Your Email Account to Lemlist
Now you’re ready for automation. Lemlist is one of the more popular email warm-up tools—because it automates a lot of tedious work. But you still need to set it up right.
2.1 Create a Lemlist Account
- Sign up for an account (choose the warm-up plan if you’re just getting started)
- You’ll need your email provider’s credentials (Gmail, Outlook, SMTP, etc.)
2.2 Connect Your Mailbox
- Go to “Settings” in Lemlist
- Add your email account (follow the prompts)
- Lemlist will check your SPF/DKIM/DMARC—fix any errors it flags
2.3 Enable Email Warm-Up
- Find the “Warm-Up” tab or section
- Switch it “ON” for your connected mailbox
- Choose your sending schedule (more on this below)
Heads up: Some features might change as Lemlist updates—if in doubt, check their docs or support.
Step 3: Customize Your Warm-Up Settings
Don’t just use the default settings and hope for the best. Here’s what actually matters:
3.1 Start Slow, Then Ramp Up
- First week: 5-10 emails per day
- Second week: 15-20 emails per day
- Third week: 25-40 emails per day
- After 3-4 weeks: You can go higher, but only if your engagement is good
Why this matters: Going from 0 to 100 makes you look like a spammer. Gradual increases build trust.
3.2 Use Realistic Content
- Lemlist sends emails between real accounts in their network
- Don’t try to game the system—let Lemlist handle content variety
- Avoid adding spammy keywords or weird formatting
3.3 Let Lemlist Manage Replies and Threading
- Lemlist’s warm-up network will automatically reply to your emails
- This simulates real conversation, which is what inboxes want to see
Don’t: Try to “speed up” the process by manually sending mass emails yourself. That’ll break the illusion and can get your domain flagged.
Step 4: Monitor Results and Adjust
Email warm-up isn’t “set it and forget it.” Watch your results and tweak as needed.
4.1 Watch Your Deliverability Metrics
- Lemlist shows how many emails landed in inbox vs. spam
- If you see lots of spam, slow things down
- If you’re seeing good inbox placement, you can ramp up a little
4.2 Check Your Domain Reputation
- Use Google Postmaster Tools or Microsoft SNDS to watch for reputation dips
- Look for blacklists—if you show up, pause sending and investigate
4.3 Keep Engagement Up
- If you’re running cold outreach, make sure people are replying
- If you’re sending newsletters, watch open and click rates
If engagement drops, you might need to slow down and troubleshoot. Sometimes, less is more.
Step 5: Transition to Real Sending—But Don’t Go Nuts
Once you’ve warmed up for at least 3-4 weeks and your deliverability looks solid, you can start regular campaigns. But don’t go from 40 emails a day to 1,000 overnight.
Best practices:
- Gradually increase your daily sending volume (e.g., 50 → 100 → 200 per day)
- Prioritize quality over quantity—targeted, relevant emails get better results and keep your reputation healthy
- Keep using Lemlist’s warm-up in the background if possible, especially if you’re scaling up fast
What to ignore: Anyone who tells you there’s a “hack” to skip the warm-up process or instantly send huge volumes from a new domain. That’s how you get burned.
Common Mistakes to Avoid
Here’s what trips people up most often:
- Skipping authentication: Your SPF/DKIM/DMARC have to be perfect. No exceptions.
- Sending mass emails too soon: Slow and steady actually wins here.
- Ignoring engagement: If people aren’t opening or replying, you’ll tank your reputation.
- Letting Lemlist run forever: Once you’re established, you don’t need to keep the full warm-up running—just monitor your reputation.
- Using spammy content: Avoid salesy phrases, all caps, or too many links, even during warm-up.
Pro Tips for Staying Out of Spam Long-Term
- Keep your lists clean. Remove bounces and unengaged contacts regularly.
- Don’t buy email lists, ever.
- Send valuable, relevant content—“spray and pray” is dead.
- Monitor your sending domains and rotate if you’re scaling up huge campaigns (but don’t overcomplicate if you’re just starting).
- Always test before sending big campaigns—use tools like Mail-Tester or GlockApps.
Keep It Simple—And Don’t Overthink It
Warming up your email domain with Lemlist isn’t rocket science. Most of it boils down to patience, common sense, and not cutting corners. Set up your domain right, use Lemlist to automate the grunt work, and listen to what your deliverability data is telling you.
You don’t need a complicated tech stack or secret hacks—just a steady process and the discipline to stick to it. If you hit a snag, slow down, check your setup, and don’t be afraid to ask for help.
The inbox is where you want to be. Stay patient, keep it real, and you’ll get there.