Why Do Cold Emails Go to Spam? Email Warmup Guide

Sending cold emails from a new email account? Here’s a painful truth: over 20% of cold emails never reach the inbox. They go straight to spam.

Why? Email providers like Gmail and Outlook don’t trust new senders. They treat you like a spammer until you prove otherwise.

The solution is email warmup, a simple 14-day process that builds your sender reputation and gets your emails into inboxes instead of spam folders.

In this guide, you’ll learn exactly how to warm up your email account, step by step, so your cold outreach actually works.

What Is Email Warmup?

Email warmup is the process of gradually building trust with email providers by slowly increasing your sending volume over 2-4 weeks.

You start by sending just 5-10 emails per day to people you know. Each day, you send a few more emails while making sure people open them and reply. This shows email providers that you’re a real person, not a spam bot.

The warmup process includes three key steps:

• Setting up email authentication (SPF, DKIM, DMARC records)
• Sending increasing volumes of emails each day (5 to 100+ emails)
• Getting positive engagement (opens, replies, no spam reports)

Without warmup, Gmail and Outlook assume you’re sending spam. With proper warmup, they trust you and deliver 85-95% of your emails to the inbox.

For B2B sales teams: If you’re using cold email to book meetings, email warmup isn’t optional. Skip it, and 70-80% of your outreach gets wasted.

Why email warmup matters for cold email?

The Cost of Landing in Spam

Let’s say you’re sending 1,000 cold emails per week. Each lead costs you $0.50 in time and tools.

Without warmup:

• Only 20-30% reach the inbox (200-300 emails)
• You waste 70-80% of your budget ($350-400/week)
• You miss out on potential deals

With proper warmup:

• 85-95% reach the inbox (850-950 emails)
• You waste only 5-15% of your budget ($25-75/week)
• More emails = more replies = more deals

Over a month, proper warmup saves you $1,300-1,500 per sales rep.

How email providers decide where your email goes?

Gmail, Outlook, and other email providers watch several signals:

• Engagement rates: Do people open, reply, or delete your emails?
• Spam reports: Does anyone mark you as spam?
• Authentication: Did you set up SPF, DKIM, and DMARC?
• Sending patterns: Are you sending 500 emails in 10 minutes? (Red flag)
• Content quality: Are you using spam trigger words?

New email accounts start with zero reputation. Email providers assume the worst until you prove you’re legitimate. That’s why warmup is essential.

How long does email warmup take?

Short answer: 14 days minimum for new email addresses. Up to 4 weeks for brand-new domains.

Factors that affect timing:

• Domain age: New domains (0-30 days old) need 4-8 weeks. Older domains need 2-3 weeks.
• Target volume: Sending 50 emails/day? Warm up for 14 days. Sending 200/day? Allow 3-4 weeks.
• Email account age: New Gmail account = start slow. Old account = faster warmup.
• Current reputation: Clean history = faster. Previous spam issues = slower.

For most B2B sales teams using tools like SmartReach: Plan for 14 days before launching your cold email campaign.

Email authentication setup (do this first)

Before you send a single warmup email, you need to set up email authentication. This tells email providers that you’re authorized to send from your domain.

SPF (Sender Policy Framework)

SPF is a DNS record that lists which servers can send email from your domain.

How to set it up:

1. Log into your domain provider (GoDaddy, Namecheap, etc.)
2. Go to DNS settings
3. Add a TXT record with your SPF information
4. Example: v=spf1 include:_spf.google.com ~all

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails so providers know they haven’t been tampered with.

How to set it up:

1. Generate DKIM keys (your email provider gives you these)
2. Add the DKIM record to your DNS settings
3. Verify it’s working with a DKIM checker tool

DMARC (Domain-based Message Authentication)

DMARC tells email providers what to do if SPF or DKIM checks fail.

How to set it up:

1. Add a DMARC record to DNS
2. Example: v=DMARC1; p=quarantine; rua=mailto:[email protected]
3. Start with p=none to monitor, then switch to p=quarantine

Important: All three (SPF, DKIM, DMARC) are required. Missing even one hurts your deliverability.

Set up your email signature

Create a professional email signature with:

• Your full name
• Job title
• Company name
• Phone number
• Website link

Avoid fake names or generic signatures like “Sales Team.” They hurt your credibility.

The 14-day email warmup schedule

Here’s your day-by-day plan to warm up a new email account:

Days	Daily Emails	What to Do
1-3	5-10	Send to friends, family, colleagues. Get 90%+ replies.
4-7	15-20	Mix of known contacts + engaged subscribers. Keep reply rate above 60%.
8-10	25-40	Add business contacts. Maintain conversations.
11-14	40-60	Scale to target volume. Test cold email templates.
15+	60-100+	Launch cold outreach. Increase by 10-15% daily if metrics are good.

Days 1-3: Foundation Phase (5-10 emails/day)

Start with people who will definitely engage with you.

What to send:

• Plain text emails (no images, no links)
• Real conversations: “Hey, how’s the project going?”
• Ask questions that require replies

Goal: 90-100% open rate and 80%+ reply rate

Avoid:

• Sending to random people
• Marketing content
• Automated messages

Days 4-7: Engagement Phase (15-20 emails/day)

Now you can add more contacts, but keep focusing on engagement.

What to do:

• Send to colleagues and business contacts
• Subscribe to 10-15 newsletters (this increases inbound email)
• Send to different email providers: Gmail, Outlook, Yahoo, Zoho
• Keep getting replies (aim for 60-70% reply rate)

Why different providers matter: Building reputation with Gmail doesn’t help with Outlook. You need to prove yourself to each one.

Days 8-10: Scaling Phase (25-40 emails/day)

You’re halfway there. Time to increase volume while maintaining quality.

What to do:

• Introduce more business contacts
• Start testing your cold email subject lines with warm contacts
• Wait 60-67 seconds between sends (don’t look like a bot)
• Monitor where your emails land (inbox vs. spam)

Pro tip: Ask a friend to check if your test emails land in their spam folder.

Days 11-14: Pre-Launch Phase (40-60 emails/day)

You’re almost ready for cold outreach.

What to do:

• Hit your target daily volume
• Test actual cold email templates with 5-10 people
• Check your deliverability with tools like Mail-Tester
• Make sure your bounce rate stays below 2%

Day 15+: Campaign Launch (Start Slow)

After 14 days, you can start cold outreach, but don’t go crazy yet.

Week 3: Send 50-60 cold emails/day
Week 4: If metrics look good (open rate >20%, bounce <2%), increase by 10-15% daily
Week 5+: Scale to your target volume (100-200 emails/day)

Important: Never stop warmup completely. Keep it running in the background at a lower volume even during active campaigns.

Manual vs. Automated Email Warmup

You have two options for warming up your email:

Manual Warmup

How it works: You personally send emails to real people and manage conversations.

Pros:

• Free (just your time)
• Natural, authentic engagement
• Full control

Cons:

• Takes 2-3 hours per day
• Hard to scale beyond 1-2 inboxes
• Easy to mess up (inconsistent sending)

Best for: Single email account, very low volume, tight budget

Automated Warmup (Recommended for Sales Teams)

How it works: Software like SmartReach automatically sends and receives emails between a network of real email accounts.

Pros:

• Takes 5 minutes to set up
• Runs 24/7 without your involvement
• Scales to unlimited inboxes
• Consistent, proven results (80-95% deliverability)

Cons:

• Costs $15-50/month per inbox (though SmartReach includes it free)

Best for: Multiple sales reps, high-volume outreach, professional teams

How SmartReach Handles Email Warmup

SmartReach.io includes automated email warmup at no extra cost:

• Set it and forget it, warmup runs automatically
• Works for unlimited email accounts
• Integrates with your cold email campaigns
• Real-time deliverability monitoring
• Inbox rotation across multiple accounts

The result: Your team can focus on selling instead of managing email warmup manually.

Email warmup best practices

Do’s ✅

• Start with 5-10 emails to people who will engage
• Maintain 60-67 seconds between sends
• Set up SPF, DKIM, and DMARC before starting
• Send to diverse email providers (Gmail, Outlook, Yahoo)
• Keep warmup running even after launch
• Use plain text emails initially
• Get real replies from real people
• Monitor your metrics weekly

Don’ts ❌

• Don’t send 100+ emails on day 1
• Don’t use purchased or scraped lists for warmup
• Don’t send to unengaged contacts
• Don’t stop warmup after 2 weeks
• Don’t use spammy subject lines
• Don’t send from 5 accounts on the same domain simultaneously
• Don’t ignore bounce rates and complaints

Monitoring your email warmup progress

Track these metrics weekly:

Key metrics:

• Inbox placement rate: Goal >90%
• Open rate: Warmup goal >60%
• Reply rate: Warmup goal >40%
• Bounce rate: Keep <2%
• Spam complaints: Keep <0.1%

Tools for monitoring:

• Google Postmaster Tools
• Mail-Tester
• MXToolbox
• SmartReach.io deliverability dashboard

Warning signs your warmup is failing:

• Emails landing in spam (>10%)
• Open rates below 30%
• Bounce rates above 5%
• Domain appears on blacklists

If you see these warning signs, pause and reduce your sending volume. Fix any authentication issues before continuing.

Conclusion

Email warmup is simple but essential. Follow the 14-day schedule, set up authentication properly, and monitor your metrics. You’ll go from zero reputation to 85-95% inbox delivery.

The choice is yours: spend 2-3 hours per day managing manual warmup, or let SmartReach.io handle it automatically while you focus on closing deals.

Ready to start? Set up your email authentication today, connect your inbox to SmartReach, and launch your automated warmup. In just 14 days, you’ll be ready to send cold emails that actually reach your prospects.

Start Your Free SmartReach Trial →

FAQ: Email Warmup

How long does email warmup take?

Email warmup typically takes 14 days for new email addresses or 2-4 weeks, depending on your target sending volume and domain age. New domains need 2-4 weeks while older domains with existing reputation may only require 1-2 weeks. The process involves gradually increasing from 5-10 emails/day to 60-100+ emails/day while maintaining high engagement rates.

What is email warmup, and why is it necessary?

Email warmup is a process that gradually improves the reputation of new or inactive email accounts to maximize deliverability. It’s necessary because email service providers treat new senders with suspicion, and over 20% of cold emails land in spam without proper warmup. Warmup builds trust with ESPs like Gmail and Outlook by demonstrating consistent, legitimate sending behavior through gradual volume increases and positive engagement.

Can I skip email warmup if I have an old domain?

No, even old domains need warmup when used for cold email campaigns. While established domains may only need 1-2 weeks compared to 2-4 weeks for new domains, the warmup process remains essential. Mailbox providers don’t care about domain age, they only evaluate current sending behavior. Dormant domains that suddenly send high volumes trigger spam filters just like new domains.

Do I need SPF, DKIM, and DMARC for email warmup?

Yes, email authentication is mandatory before starting warmup. SPF authorizes servers to send on your domain’s behalf, DKIM provides a digital signature to prevent email manipulation, and DMARC requires both authentications before allowing delivery. Without proper DNS configuration, even perfectly warmed accounts will face deliverability issues.

Should I use manual or automated email warmup?

Automated warmup is recommended for most use cases, especially B2B sales teams. Manual warmup works if you’re sending 10-20 emails/day from a single inbox, but managing multiple inboxes or scaling requires automation for safety and efficiency. Manual warmup costs time; automated costs $15-50/month per inbox.

Can I send cold emails during the warmup process?

It’s not recommended to run high-volume campaigns during the first 2 weeks of warmup for new mailboxes. However, after 2 weeks of warmup, you can start sending campaign emails at low volume with highly engaging content. Begin with 10-20 cold emails/day alongside your warmup emails, then gradually increase to your target volume over the next 1-2 weeks.

What happens if I stop email warmup after the initial period?

Stopping warmup after the initial phase will cause your deliverability and sender reputation to suffer, warmup should run continuously. Email warmup is an ongoing process, not a one-time task, as sender reputation degrades without consistent positive engagement. Dormant activity reverses the warmup process, ESPs interpret reduced sending as account abandonment.