Cold email deliverability
The mechanics that decide whether your outbound lands in primary, promotions, or quarantine.
Cold email deliverability is the collection of infrastructure, sender-reputation, content, and recipient-behavior factors that determine whether a programmatically-sent email reaches the recipient's primary inbox, a secondary tab, the spam folder, or is dropped silently by the mailbox provider.
What actually moves inbox placement.
Infrastructure
Domain age, DNS records (SPF, DKIM, DMARC), MX provider, IP reputation, and sending-domain segmentation.
Sender reputation
Google Postmaster signals, complaint rate, spam-trap hits, and the rolling history of how recipients have engaged with your domain.
Content signals
Subject patterns, link density, image-to-text ratio, footer hygiene, and per-sequence variance.
Recipient behavior
Opens, replies, archives, and the all-important "mark as not spam" — the strongest deliverability signal that exists.
The vocabulary you actually need.
- SPF
- Sender Policy Framework — DNS record that lists who is allowed to send mail on behalf of your domain.
- DKIM
- DomainKeys Identified Mail — cryptographic signature that proves a message was not altered in transit.
- DMARC
- Policy layer that tells receivers what to do when SPF or DKIM fails (none / quarantine / reject).
- Postmaster Tools
- Google's diagnostic console for sending domains — the only authoritative view of how Gmail sees you.
- Warmup
- Process of gradually increasing send volume on a new domain to build sender reputation before campaign traffic.
- Spam trap
- Email address used by mailbox providers and blacklists to identify senders with poor list hygiene.
Deliverability, in practice.
If the domain still has reputation salvageable (no recent blocklist hits, no spam-trap exposure), 4–6 weeks of disciplined warmup and content normalization. If the domain is burnt, faster to retire it and ship traffic on a new sending domain.
More on cold email engines.
Clay waterfall teardown: 7 sources, one canonical record
An annotated walkthrough of a production Clay enrichment graph — sources, dedup logic, and the cost of every column.
MQL→SQL routing: speed-to-lead, ownership, and the SLA that holds
A field guide to the routing layer between marketing interest and sales action — built from 40+ engagements.
The LinkedIn signal stack we actually use
Hiring, posting cadence, comment graph, and tenure — the four signals that decide whether to open a conversation.
Audit your sending infrastructure in one call.
We will pull your DNS, Postmaster, and warmup state on a screen-share and tell you what to fix this week — and what to retire.