Published April 26, 2026 · 14 min read
Make sure your SPF, DKIM, DMARC, and MTA-STS records are configured correctly before sending a single email.
Free Domain Check →Starting to send email from a brand new domain — or suddenly increasing volume from an existing one — without a proper warmup is one of the fastest ways to destroy your deliverability. ISPs like Gmail, Outlook, and Yahoo evaluate sender reputation partly based on historical sending patterns. A domain with no history that suddenly sends 10,000 emails is essentially screaming "I might be a spammer."
Email warmup is the process of gradually increasing your sending volume over weeks to build a positive reputation with inbox providers. This guide covers both IP warmup and domain warmup, with specific daily schedules, monitoring strategies, and common mistakes to avoid.
| Factor | IP Warmup | Domain Warmup |
|---|---|---|
| What it builds | Reputation for the sending IP address | Reputation for your domain name |
| Who tracks it | ISPs (Gmail, Outlook) per IP | ISPs (Gmail, Outlook) per domain |
| Duration | 2-4 weeks | 4-8 weeks (longer for new domains) |
| Can you skip it? | Yes, if using a pre-warmed shared or dedicated IP from an ESP | No — every new domain needs warmup regardless |
| Risk if skipped | Reputation damage to that specific IP | Reputation damage to your entire brand domain |
Key point: Even if you use a shared IP at Mailchimp, SendGrid, or another ESP (where the IP is already warmed), you still need to warm up your domain. Domain reputation is tracked independently from IP reputation at every major ISP.
Do not send a single email until these are in place:
v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. Configure DMARC →Goal: Establish a baseline reputation. Send only to your most engaged contacts — people who opened or clicked an email in the last 30 days.
| Day | Daily Volume | Who to Send To |
|---|---|---|
| Day 1 | 20-50 emails | Top 20 engaged contacts |
| Day 2 | 50-75 emails | Top 50 engaged contacts |
| Day 3 | 75-100 emails | Top 75 engaged contacts |
| Day 4 | 100-150 emails | Top 100 engaged contacts |
| Day 5 | 150-200 emails | Top 150 engaged contacts |
| Day 6 | 200-250 emails | Top 200 engaged contacts |
| Day 7 | 250-350 emails | Top 300 engaged contacts |
Goal: Increase volume gradually. Continue prioritizing engaged recipients.
| Day | Daily Volume | Who to Send To |
|---|---|---|
| Day 8 | 350-500 emails | Engaged (opened in 60 days) |
| Day 9 | 500-700 emails | Engaged (opened in 60 days) |
| Day 10 | 700-900 emails | Engaged (opened in 60 days) |
| Day 11 | 900-1,100 emails | Engaged (opened in 90 days) |
| Day 12 | 1,100-1,400 emails | Engaged (opened in 90 days) |
| Day 13 | 1,400-1,700 emails | Engaged (opened in 90 days) |
| Day 14 | 1,700-2,000 emails | Engaged (opened in 90 days) |
Goal: Continue ramping volume. You can begin including moderately engaged contacts (opened in the last 6 months).
For very high-volume senders (50,000+ emails/day), continue the 20-30% ramp every 2-3 days until reaching target volume. Most senders under 10,000 emails/day can be at full volume by week 4-5.
During warmup, monitor these metrics daily:
DMARC aggregate reports show you which mail is passing or failing authentication. Run DMARC in p=none mode during warmup to collect data without affecting delivery:
# Set your DMARC record to monitoring mode during warmup v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com; ri=86400
After warmup, once you're confident authentication is working, move to p=quarantine and then p=reject. Read our full DMARC setup guide →
Check your domain's authentication score regularly with our API:
# Check your domain's deliverability health
curl https://korpo.pro/api/v1/check/yourdomain.com
# Batch check multiple sending domains
curl -X POST https://korpo.pro/api/v1/batch \
-H "Content-Type: application/json" \
-d '{"domains":["send.yourdomain.com","news.yourdomain.com"]}'
The response includes a 0-100 score broken down by protocol. Your goal is 90+ before reaching full volume.
Inbound marketing emails and transactional emails warm up naturally because they go to verified, engaged recipients. But cold outreach (sales emails to prospects who haven't opted in) requires special care:
outreach.yourdomain.com) so it doesn't affect your primary domain's reputationUsing a dedicated subdomain for marketing or transactional email is a best practice — it isolates your primary domain's reputation:
| Strategy | Subdomain | Reputation Impact |
|---|---|---|
| Primary domain | yourdomain.com | Marketing problems affect everything |
| Marketing subdomain | news.yourdomain.com | Isolated — protects yourdomain.com |
| Transactional subdomain | mail.yourdomain.com | Isolated — protects yourdomain.com |
| Cold outreach | outreach.yourdomain.com | Isolated — protects yourdomain.com |
Each subdomain needs its own warmup. The good news: subdomains inherit some trust from the root domain, so warmup may be slightly faster (3-4 weeks instead of 4-6).
Each subdomain sending email needs its own SPF, DKIM, and DMARC records:
# SPF for subdomain news.yourdomain.com TXT "v=spf1 include:mailchimp.com ~all" # DKIM selector for subdomain k1._domainkey.news.yourdomain.com TXT "v=DKIM1;k=rsa;p=MIGfMA..." # DMARC for subdomain (inherits from root unless overridden) _dmarc.news.yourdomain.com TXT "v=DMARC1;p=quarantine;rua=mailto:dmarc@yourdomain.com"
The most common warmup failure is ramping volume too quickly. Going from 0 to 5,000 emails/day in a week will trigger spam filters. The 20-30% increase every 2-3 days rule exists for a reason — ISPs evaluate your sending pattern over rolling 30-day windows, not just today's volume.
Purchased lists have high bounce rates and complaint rates. Using them during warmup — when your domain has no positive history to offset the damage — is catastrophic. Only warm up with contacts who have explicitly opted in to receive your email.
ISPs expect consistent sending behavior. If you send 1,000 emails on Monday, nothing Tuesday-Thursday, and 5,000 on Friday, that's a red flag. Send at consistent volumes on consistent days. Consistency matters more than volume.
Starting warmup without SPF, DKIM, and DMARC records in place means ISPs can't authenticate your email — which makes the warmup pointless. Check your DNS records first →
During warmup, DMARC reports tell you if your authentication is working. If DKIM or SPF is failing for some receivers, you need to fix it before ramping volume. Set up DMARC reporting →
Track your domain's deliverability health throughout warmup with automated checks:
# Weekly check during warmup
curl https://korpo.pro/api/v1/check/yourdomain.com | jq '.score'
# Set up alerts: if score drops below 80, pause warmup
# Example cron (Sundays at 9am):
0 9 * * 0 curl -s https://korpo.pro/api/v1/check/yourdomain.com | jq '.score' > /tmp/warmup-score.txt
# Check multiple sending subdomains
curl -X POST https://korpo.pro/api/v1/batch \
-H "Content-Type: application/json" \
-d '{"domains":["news.yourdomain.com","mail.yourdomain.com","outreach.yourdomain.com"]}'
| Week | Daily Volume | Recipients | Key Monitoring |
|---|---|---|---|
| Week 1 | 20-350 | Most engaged (30-day) | Bounce rate, opens |
| Week 2 | 350-2,000 | Engaged (60-90 day) | + Complaint rate |
| Week 3 | 2,000-5,000 | Engaged (90-180 day) | + DMARC reports |
| Week 4 | 5,000-10,000 | Moderately engaged | + Domain reputation tools |
| Week 5-8 | 10,000+ | Full list (with hygiene) | + Blacklist monitoring |
A proper domain warmup takes 4-8 weeks. IP warmup takes 2-4 weeks. The timeline depends on your target volume — domains sending under 5,000 emails/day can warm up in 3-4 weeks, while high-volume senders (50,000+/day) should plan for 6-8 weeks.
If you're on a shared IP at a major ESP (like Mailchimp or SendGrid), the IP is already warmed. But you still need to warm up your domain reputation separately — domain warmup is about establishing a positive sending history for your domain name, independent of the IP.
Sending high volume from a cold domain triggers spam filters. You'll see high bounce rates, spam folder placement, and potential blacklisting. Recovery from a damaged domain reputation takes 3-6 months — much longer than the 4-6 weeks a proper warmup requires.
Automated warmup tools that send emails to networks of fake accounts can actually harm your reputation. Gmail and Outlook detect these networks and penalize domains using them. Instead, warm up by sending real, valuable email to engaged recipients.
Keep your complaint rate below 0.1% (1 complaint per 1,000 emails delivered). If it exceeds 0.3%, stop sending immediately and investigate. During the first week of warmup, aim for near-zero complaints by only emailing your most engaged contacts.
Before you send a single email, make sure SPF, DKIM, DMARC, and MTA-STS are configured correctly. One DNS error can waste weeks of warmup effort.
Free Domain Check →