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In outbound marketing, success isn’t just about the strength of your message or the precision of your targeting. If your emails don’t land in the inbox, none of your GTM motion matters. As deliverability standards tighten across mailbox providers, domain warming has become a non-negotiable step for any team that sends cold emails at scale.
In this edition of GTM Society, we unpack what domain warming is, why it matters, and the best practices high-performing GTM teams follow to build a healthy sender reputation from day one.
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What Exactly Is Domain Warming?
Domain warming is the gradual process of increasing the volume of emails sent from a new domain (or a dormant one) to build a positive sender reputation with mailbox providers like Gmail, Outlook and Yahoo.
Think of it as a credit score for your domain. ISPs track how recipients respond to your emails — opens, clicks, replies, complaints, bounces — and use these signals to judge whether your messages deserve a place in the inbox or the spam folder. A domain that suddenly sends hundreds or thousands of emails from day one is immediately flagged as suspicious.
Warming ensures the domain introduces itself to mailbox providers slowly, consistently and with strong engagement, marking you as a trustworthy sender rather than a potential spammer.
Why Domain Warming Matters for GTM Teams
GTM motions increasingly rely on cold outbound — whether that’s SDR sequences, partner outreach, event invites or ABM campaigns. But with rising global spam volumes and provider-side enforcement, even legitimate senders face tougher scrutiny.
A properly warmed domain unlocks:
Inbox Placement: Higher reputation translates to more emails reaching primary inboxes rather than promotions or spam.
Consistent Deliverability: Avoid sudden drops in performance or domain-level blacklisting.
Reliable Scale: As your outreach grows from dozens to hundreds to thousands per day, warming ensures the domain can handle higher volumes safely.
Better Metrics Across the Funnel: More inbox visibility means more opens, clicks, replies and pipeline creation.
Skipping warming isn’t just risky — it’s expensive. Poor deliverability compounds into wasted efforts, inaccurate reporting, SDR burnout, and ultimately, deals lost before they even start.
How the Domain Warming Process Works
At a high level, warming a domain follows four phases:
1. Setup Phase
Before sending anything, ensure your authentication protocols are ready:
SPF
DKIM
DMARC
Custom domain tracking links
A/B test the domain address format
These records verify your identity and prevent spoofing — giving providers confidence in the legitimacy of your emails.
2. Slow Introduction Phase (Days 1–7)
Send 10–30 emails per day to highly engaged contacts — ideally warm leads, internal employees or opted-in lists. These early signals are crucial for establishing trust.
3. Controlled Ramp Phase (Weeks 2–3)
Gradually double daily volume every few days as long as engagement remains high and complaint rates stay low. Shift from friendly contacts to colder prospects as reputation solidifies.
4. Scale and Maintain Phase (Week 4 onwards)
Once your domain is delivering consistently, scale to your full daily volume (usually 500–2,000 emails per day depending on your GTM goals). Maintain healthy sending patterns and avoid sudden spikes.
Domain warming is not a one-time task. It’s an ongoing discipline to keep sender reputation strong.
Best Practices for Successful Domain Warming
Here are the practices that top outbound teams consistently follow:
1. Start with High-Quality Contacts
The first recipients of your emails should be people who are likely to open, click or reply — colleagues, partners, past customers, newsletter subscribers. Positive engagement accelerates trust-building.
2. Maintain a Consistent Sending Schedule
Send emails daily at predictable volumes. Sudden jumps, pauses or spikes can immediately harm your reputation.
3. Use High-Quality Copy in the Early Stages
Warm-up emails must feel personal, relevant and easy to respond to. Avoid sales-heavy language during the early phase.
4. Monitor Key Metrics Closely
Track:
Open rates
Reply rates
Bounce rates
Spam complaints
Spam placement
If you see negative trends, pause warming and correct issues before scaling.
5. Keep Bounce Rates Under 3%
High bounce rates signal spam behaviour. Validate lead lists before sending, especially once you begin cold outreach.
6. Avoid Automation in the First Week
Manual sends (or low-volume automation) help you maintain control over quality and prevent mistakes.
7. Use Multiple Domains for Large Teams
If your GTM engine runs thousands of sequences per day, spread the load across multiple warmed domains to avoid overload.
8. Maintain Strong List Hygiene
Regularly remove inactive leads and honor all unsubscribe/opt-out requests immediately.
9. A/B Test Your Sender Name and Email Structure
Small variations can impact engagement and deliverability. Test sender titles, domain sub-addresses, and signature formats.
Final Thoughts
Domain warming is one of the most overlooked yet essential components of a modern outbound strategy. It is the first step in ensuring your GTM efforts are seen, read and acted upon. When done correctly, it improves deliverability, boosts campaign performance and provides a solid foundation for scalable outbound growth.
For GTM-driven teams, a well-warmed domain isn’t just technical hygiene — it is competitive advantage.
Until next time,
— Team GTM Society