Warming Up Your Domain

Domain warming is the process of gradually building sender reputation with email providers. Skip this step and your emails will land in spam. Follow this guide to warm up properly.

Why Warming Matters

Email providers (Gmail, Outlook, etc.) are suspicious of new sending domains. They watch for patterns that indicate spam:

New domain suddenly sending 1,000 emails/day = spam
Established domain gradually increasing from 50 to 500/day = legitimate

Warming builds trust by demonstrating consistent, legitimate sending behavior.

Who Needs to Warm Up?

⚠️ Definitely Need Warming

Brand new domain (< 3 months old)

New custom email (e.g., just set up john@newstartup.com)

Domain with no sending history

Switching from Gmail personal to custom domain

✅ May Skip Warming

Gmail account with 2+ years of regular use

G Suite/Workspace account used for business emails

Domain with established sending history (already sending 100+ emails/day)

Warming Schedule (4-6 Weeks)

Week 1: Establish Baseline

Daily volume: 20-50 emails
Who to email: Warm contacts (colleagues, existing customers, partners)
Goal: Get positive engagement (opens, replies) from trusted contacts

Week 2: Gradual Increase

Daily volume: 50-100 emails
Who to email: Mix of warm + lightly targeted cold outreach
Goal: Maintain high engagement rate (> 10% open rate)

Week 3: Scale Up

Daily volume: 100-200 emails
Who to email: Primarily cold outreach to qualified leads
Goal: Monitor bounce rate (< 2%) and spam complaints (< 0.1%)

Week 4: Continue Growth

Daily volume: 200-400 emails
Who to email: Full cold outreach campaigns
Goal: Consistent metrics, no sudden spikes in negative signals

Week 5-6: Reach Target Volume

Daily volume: Up to provider limit (500-2,000/day)
Who to email: Full-scale campaigns
Goal: Warm-up complete, inbox placement rate 95%+

Warming Best Practices

1. Start with Engaged Contacts

First emails should go to people likely to open and reply:

Coworkers and team members
Existing customers
Business partners
People who recently visited your website
LinkedIn connections who engaged with your content

2. Avoid Sudden Volume Spikes

❌ Bad: 50 emails Mon-Fri, then 500 on Saturday

✅ Good: 50, 55, 60, 65, 70 (gradual daily increase)

3. Maintain Consistency

Send similar volumes every day (don't skip days)
Spread sends throughout the day (not all at once)
Stick to business hours (9 AM - 5 PM recipient timezone)

4. Monitor Engagement Metrics

During warm-up, track these closely:

Open rate: Aim for 20%+ (lower = potential deliverability issue)
Reply rate: Aim for 3%+ positive replies
Bounce rate: Keep under 2%
Spam complaints: Must stay under 0.1%

Warming with WarmOpener

Setting Daily Limits

Go to Inboxes page
Edit your connected inbox
Set Daily Send Limit according to warming schedule
Week 1: Set to 50/day
Increase limit weekly as you progress through schedule

Campaign-Level Limits

You can also set per-campaign daily limits:

Launch campaign to 500 contacts
Set campaign daily limit to 50
Campaign will pace itself: 50/day × 10 days = all 500 contacts emailed
Increase limit as warming progresses

Automating the Warm-up

Warm-up Services (Optional)

These services automate domain warming by sending/receiving emails between their network:

Warmup Inbox: $69/mo, automatic warm-up over 4-8 weeks
Mailwarm: $79/mo, includes deliverability monitoring
Lemwarm: $25/mo, basic automated warming

Pros: Hands-off, guaranteed engagement
Cons: Additional cost, not as effective as real engagement from real prospects

Signs Your Warm-up is Working

✅ Emails consistently landing in inbox (not spam)

✅ Open rates stable or increasing (15-25% for cold email)

✅ Bounce rate consistently under 2%

✅ No spam complaints or very few (< 0.1%)

✅ Google Postmaster Tools shows "High" or "Medium" reputation

Common Warm-up Mistakes

❌ Rushing the Process

Going from 50 to 500 emails/day in week 2. Take the full 4-6 weeks.

❌ Starting with Cold Lists

Sending to purchased lists during warm-up. Start with warm, engaged contacts.

❌ Inconsistent Sending

Sending 200 Monday, 0 Tuesday-Thursday, 300 Friday. Send consistently every day.

❌ Ignoring Bounce Rates

Continuing to send despite 10% bounce rate. Clean your list immediately if bounces spike.

⚠️ Don't Skip Warming

We see this often: excited user signs up, imports 2,000 contacts, launches campaign day 1, sends 500 emails. Result: 80% spam folder, domain reputation destroyed, months to recover.

Take the 4-6 weeks to warm up properly. It's not exciting, but it's essential. Your future self (and your inbox placement rate) will thank you.

💡 Pro Tip

Use WarmOpener's campaign daily limit feature to enforce warming schedule. Set limit to 50 day 1, increase by 10-20 every 3-4 days. This prevents accidentally sending too much volume early on. Once warm-up complete (6 weeks), remove campaign limits and rely on inbox daily limits.