Cold Email Deliverability

Cold email deliverability refers to the ability of your outbound emails to reach the recipient's primary inbox rather than their spam folder or being blocked entirely. Deliverability is arguably the single most important technical factor in cold email performance — a campaign with a 50% open rate earns 3x more replies than the same campaign at 15%, regardless of copy quality.

Key deliverability factors include:

Domain Reputation: How email providers perceive your sending domains based on volume, bounce rate, spam complaints, and sending history. New domains must be warmed over 2–4 weeks before sending at full volume.

SPF, DKIM, DMARC: Authentication records that prove to receiving servers that you own your sending domain. Missing these records is the fastest path to permanent spam folder placement.

Inbox Warmup: Gradually increasing send volume while building positive sending reputation signals (opens, replies, moves to primary).

Bounce Rate: Emails sent to invalid addresses signal poor list quality. A bounce rate above 3–5% damages domain reputation. Waterfall enrichment keeps bounce rates below 2%.

Spam Complaints: Recipients marking emails as spam is the most damaging deliverability signal. Relevance, personalization, and clear unsubscribe mechanisms reduce spam complaints.