Great cold email copy is useless in spam. I’ll say it bluntly: if your deliverability is broken, nothing else in your sequence matters.
Most teams only think about cold email deliverability after opens collapse. In this guide, I’ll walk you through the 4 pillars we fix first for UK founders—so you don’t scale a leaking bucket.
What is cold email deliverability?
Deliverability is your ability to land in the inbox consistently. Not “sent.” Not “delivered to spam.” Inbox.
Providers look at authentication, reputation, engagement, complaints, and content patterns. Skip one pillar and the others get harder.
Pillar 1: authenticate your domain (SPF, DKIM, DMARC)
Before you write a single cold email, set SPF, DKIM, and DMARC on the sending domain. This is table stakes in 2026.
If authentication is messy, inbox providers treat you like a risk—even if your copy is perfect.
- Use a dedicated sending domain or subdomain for outreach
- Set SPF, DKIM, and DMARC correctly
- Keep your primary brand domain separate from cold sending
Pillar 2: warm infrastructure before you scale
New domains need trust. Warm gradually. Start low. Increase only when placement looks healthy.
Rushing volume is the fastest way to train filters that you are spam.
- Week 1: low daily volume, high-quality contacts only.
- Week 2: increase slowly if opens/replies look normal.
- Week 3+: scale only after reputation is stable.
Pillar 3: protect list quality like revenue
Verify emails. Remove role accounts that don’t fit. Stop sequences that create complaints.
A smaller verified list will outperform a scraped “10,000 leads” dump every week of the year.
If you want campaigns handled end to end—copy, deliverability, and inbox management—see our cold email outreach service.
