How to Warm Up Your Email Domain (Step-by-Step Guide)

If you buy a new domain and immediately start sending 200 cold emails per day, you'll land in spam within a week. Email providers don't trust new domains — they have no sending history, no reputation, and no proof they're legitimate.

Domain warmup solves this by gradually building your sender reputation. Done right, your emails land in the inbox consistently. Done wrong — or skipped entirely — and even great cold emails go unread in spam folders.

What Is Email Domain Warmup?

Email warmup is the process of gradually increasing your sending volume over several weeks while maintaining high engagement (opens, replies). It signals to Gmail, Outlook, and other providers that your domain sends emails people actually want to receive.

Think of it like a new employee. You wouldn't give them 200 client calls on day one — you'd start small, build trust, then increase responsibility. Same principle applies to a new sending domain.

Step 1 — Set Up Your DNS Records Correctly

Before sending a single email, set up these 3 DNS records. Without them, even warmed-up domains will have deliverability problems.

SPF (Sender Policy Framework)

SPF tells receiving mail servers which IP addresses are allowed to send email from your domain. Without SPF, your emails are more likely to be marked as spam.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails that proves they weren't tampered with in transit. Most email providers generate DKIM records for you — look in your email provider's settings.

DMARC

DMARC tells receiving servers what to do when emails fail SPF or DKIM checks. Start with a monitoring-only policy:

After 2–4 weeks, change p=none to p=quarantine or p=reject.

Step 2 — Use a Subdomain for Cold Email

Never send cold emails from your main business domain (e.g. yourcompany.com). If your cold email reputation drops, it will affect your main domain's deliverability — including your regular business emails.

Instead, use a subdomain or a separate domain for cold outreach:

• yourcompany.co (alternative TLD)
• getyourcompany.com
• tryyourcompany.com
• helloyourcompany.com

Step 3 — Follow a Warmup Schedule

Increase your daily sending volume gradually over 4–8 weeks. Here's a recommended schedule:

Step 4 — Monitor These Metrics

During warmup, watch these numbers closely:

• Bounce rate — Keep below 2%. Above 5% and you need to pause and fix your list.
• Spam complaint rate — Keep below 0.1%. Google will throttle you above this.
• Open rate — Should be 30–60% during warmup (warmup emails get opened). Real campaigns: aim for 40%+.
• Reply rate — Warmup emails should get replies to signal engagement to email providers.

Step 5 — Use Automated Warmup Tools

Manual warmup is slow and inconsistent. Warmup tools automate the process by sending emails between a network of real inboxes and automatically opening, replying to, and marking your emails as not-spam.

Popular warmup tools include:

• ReachHighly — Built-in warmup system included on paid plans. No extra setup needed.
• Warmup Inbox — Standalone warmup tool, works with any email provider.
• Mailwarm — Simple warmup tool, good for beginners.
• Lemwarm (by Lemlist) — Popular warmup network with real inboxes.

Common Warmup Mistakes to Avoid

• Skipping warmup entirely — The most common mistake. New domains sent at volume go straight to spam.
• Warming up too fast — Jumping from 10 to 200 emails in a week triggers spam filters.
• Sending to bad lists during warmup — High bounces during warmup permanently damages your reputation.
• Stopping warmup too early — 4 weeks minimum, 8 weeks for best results.
• Using your main domain — Always use a separate domain for cold outreach.

Frequently Asked Questions