Email Warmup: How to Warm Up a New Domain or IP

Domain & Sender Reputation

New email domains and IP addresses start with no reputation. Email providers don't know whether you're a legitimate sender or a spammer setting up shop. Warmup is the process of gradually building sending reputation so you can eventually send at full volume without deliverability problems.

Why Warmup Matters

The New Sender Problem

Email providers are cautious about new senders. Spammers constantly register new domains and acquire new IPs to escape the reputation damage on their previous infrastructure. To protect users, providers scrutinize email from unknown sources more heavily.

A brand new domain sending 50,000 emails on day one looks suspicious. That's not how legitimate businesses typically operate. It looks like someone trying to blast out spam before getting caught.

What Happens Without Warmup

If you skip warmup and send at volume immediately:

• Emails may be heavily throttled or blocked
• Many messages land in spam
• IP or domain may be blacklisted
• Recovery becomes more difficult than starting properly

The damage from a failed launch can take weeks or months to repair — far longer than a proper warmup would have taken.

When You Need to Warm Up

New Domain

Any domain that's never sent email before needs warmup. Even if the domain has existed for years as a website, if it hasn't sent email, it has no email reputation.

New IP Address

Moving to a new dedicated IP requires warmup. The IP has no sending history, so providers don't know whether to trust it.

Returning After Long Dormancy

If a domain or IP hasn't sent email in months, reputation may have decayed or reset. A gradual ramp-up is safer than immediately returning to previous volumes.

Changing Email Service Providers

Moving to a new ESP often means new infrastructure. Even if your domain reputation is established, the new sending IPs need time to build trust.

The Warmup Process

Phase 1: Foundation (Week 1-2)

Start with very small volumes to your most engaged contacts:

Day 1-3: 50-100 emails per day Day 4-7: 100-250 emails per day Week 2: 250-500 emails per day

Who to email:

• Recent subscribers (last 30-60 days)
• Contacts who regularly open and click
• People who have replied to previous emails
• Internal team members for testing

Why engaged contacts first:

• They're likely to open (positive signal)
• Less likely to mark as spam
• Establishes positive engagement patterns from the start

Phase 2: Scaling (Week 3-4)

Gradually increase volume while monitoring metrics:

Week 3: 500-1,000 emails per day Week 4: 1,000-2,500 emails per day

Who to add:

• Moderately engaged contacts
• Subscribers from the past 90-180 days
• Contacts with some engagement history

What to monitor:

• Bounce rates (should stay under 2%)
• Spam complaints (should stay under 0.1%)
• Open rates (should remain healthy)
• Delivery rates (should stay above 95%)

Phase 3: Approaching Full Volume (Week 5-8)

Continue scaling toward your target volume:

Week 5-6: 2,500-5,000 emails per day Week 7-8: 5,000-10,000+ emails per day

Adjustments:

• Add less engaged segments gradually
• Monitor for any deliverability drops
• Slow down if metrics deteriorate
• Provider-specific issues may require attention

Phase 4: Full Volume

After 4-8 weeks (depending on target volume), you should be able to send at your intended rate. Continue monitoring — reputation needs ongoing attention.

Warmup Best Practices

Authenticate Before Anything Else

Set up authentication before sending a single email:

• Configure SPF to include your sending service
• Enable DKIM signing for your domain
• Publish DMARC record for monitoring

Authentication problems compound during warmup. Fix them first.

Maintain Consistency

Send every day during warmup:

• Gaps in sending slow reputation building
• Weekend drops are okay but maintain some activity
• Sudden spikes look suspicious

Monitor Aggressively

Watch metrics closely during warmup:

• Check Google Postmaster Tools daily (if sending to Gmail)
• Monitor bounce and complaint rates after each send
• Track inbox placement through test seeds
• Watch for blacklist listings

Prioritize Engagement

The goal is building positive signals:

• Send your best content during warmup
• Use compelling subject lines
• Include clear calls to action
• Encourage replies where appropriate

Be Ready to Pause

If you see warning signs, slow down or pause:

• Bounce rate spikes
• Complaint increases
• Delivery rate drops
• Blacklist listings
• Postmaster reputation drops

Better to extend warmup than damage reputation.

Provider-Specific Considerations

Gmail

Gmail is often the largest portion of recipients and has sophisticated filtering:

• Watch Google Postmaster Tools reputation closely
• Gmail is sensitive to complaint rates
• Promotional tab placement is common initially
• Building Primary inbox placement takes time

Microsoft (Outlook, Office 365)

Microsoft can be strict about new senders:

• DMARC enforcement is strict
• Register with Microsoft SNDS for data
• Corporate Office 365 recipients may have additional filtering
• May need longer warmup for Microsoft domains

Yahoo/AOL

Yahoo watches complaint rates very closely:

• Enroll in Yahoo's Complaint Feedback Loop
• Keep complaint rates especially low
• Yahoo may be more aggressive about blocking during warmup

Warmup Timeline Examples

Low Volume Sender (Target: 5,000/week)

Full volume reached in approximately 4 weeks.

Medium Volume Sender (Target: 50,000/week)

Full volume reached in approximately 6 weeks.

High Volume Sender (Target: 500,000/week)

Full volume reached in approximately 8-10 weeks.

Warmup Services

Several services automate warmup:

What They Do

• Send emails on your behalf to establish reputation
• Often send to their own network of recipients
• Automatically increase volume on schedule
• Some generate artificial engagement

Considerations

• Effectiveness varies widely
• Some providers view this skeptically
• Organic engagement is more valuable
• May be useful supplement, not replacement for real warmup

When Warmup Goes Wrong

Signs of Problems

• Delivery rate below 90%
• Bounce rate above 3%
• Complaint rate above 0.2%
• Postmaster reputation declining
• Blacklist listings appear

Recovery Steps

1. Pause sending — Stop the damage
2. Investigate — Identify what went wrong
3. Fix issues — Authentication, list quality, content
4. Resume slowly — Start warmup over from lower volume
5. Monitor closely — Watch for recurring issues

When to Restart

Sometimes it's better to start fresh:

• Severe reputation damage
• Multiple blacklist listings
• Can't identify the cause
• New domain may be cleaner option

Stop Worrying About Email Deliverability

The Email Deliverability Suite monitors your SPF, DKIM, DMARC, MX records and blacklist status daily. Get alerts when something breaks — before your emails stop arriving.