Cold email deliverability checklist

A cold email deliverability checklist covers four pillars before you send: buy and configure separate sending domains, warm up each mailbox for two to three weeks, set SPF, DKIM, and DMARC records, and verify your list. Get these right and inbox placement follows. Skip one and spam folders follow.

Why does cold email land in spam?

Cold email lands in spam when mailbox providers see risk signals: a cold domain with no reputation, missing authentication, a spike in send volume, or a list full of dead addresses. Each bad signal compounds. Providers like Google and Microsoft filter on sender behavior, not just content. Fix the signals first.

The checklist below runs in a deliberate order. Domains and inboxes come first because reputation takes weeks to build and cannot be rushed. Warmup and authentication run in parallel over the next two to three weeks. List verification comes last, right before you load contacts into your sequencer, since lists decay day by day. Work top to bottom and you never send from an unprepared mailbox.

None of this requires deep technical skill. Most of the setup is one-time work, done in an afternoon of DNS edits and inbox creation. The recurring effort is verification and monitoring, and both take minutes once the foundation is solid. The order matters more than the difficulty.

Set up dedicated sending domains and inboxes

Never send cold email from your primary domain. A single complaint spike can damage the domain your whole company relies on for invoices, contracts, and normal mail. Register separate domains for outreach, ideally close variants of your brand. On each domain, create only two or three inboxes. Redirect the cold domain to your main site so links in your emails resolve to a real page.

Keep per-inbox volume low. A safe ceiling is 30 to 50 emails per inbox per day once the mailbox is warm. To reach 500 sends a day, spread the load across ten mailboxes rather than pushing one inbox harder. More inboxes at low volume beats fewer inboxes at high volume every time, and it limits the damage if one mailbox gets flagged.

Warm up every mailbox before the first campaign

A brand new mailbox has zero reputation. Sending 50 cold emails on day one is the fastest route to the spam folder. Warmup means ramping volume slowly while generating positive engagement: opens, replies, and messages pulled out of spam. Automated warmup tools simulate this activity between real accounts, and most sequencers bundle one at no extra cost.

Plan two to three weeks minimum before your first real send. Start at 5 to 10 emails a day and increase gradually. Keep warmup running quietly in the background even after campaigns launch. It maintains reputation between sends and cushions the occasional bad day, like a batch of hard bounces or a spam complaint.

What authentication records does cold email need?

Cold email needs three DNS records on every sending domain: SPF to list servers allowed to send for you, DKIM to cryptographically sign each message, and DMARC to tell providers how to handle failures. Without all three, Google and Yahoo bulk-sender rules route you straight to spam or reject you outright.

Set DMARC to p=none while you monitor the aggregate reports, then tighten to quarantine or reject once SPF and DKIM pass consistently. Google and Yahoo now require authentication for anyone sending in volume, so this is not optional. Send yourself a test message and confirm the headers show all three checks passing before any real campaign goes out.

Verify your list before the first send

A verified list is the single biggest lever you have on bounce rate. Mailbox providers watch bounces closely, and a bad first campaign is hard to recover from. Keep your bounce rate under 2 percent or reputation drops fast. Scrub every list, even one exported from a reputable data provider, because addresses decay at roughly 2 to 3 percent per month as people change jobs and companies fold.

Verification catches invalid syntax, dead mailboxes, duplicates, and disposable domains before they cost you. It flags catch-all and role addresses like info@ and sales@ as risky so you can decide case by case whether to send. The Free Email Verifier runs MX-record and SMTP-level mailbox checks, suggests typo fixes, and exports a clean CSV or JSON ready to drop into your sequencer.

Send like a human once you launch

Configuration gets you to the inbox. Behavior keeps you there. Keep early messages plain text with no images, no tracking pixels, and at most one link. Heavy HTML and link-stuffed footers read as bulk mail. Personalize the first line so replies come naturally, because replies are the strongest positive signal a mailbox can earn. Throttle sends across the workday rather than firing a batch at 9 a.m. sharp. Stop a sequence the moment someone replies or bounces, and suppress every hard bounce so you never hit it twice.

Watch your metrics daily for the first two weeks. If open rates sag or bounces climb, pause and diagnose before scaling. A quick seed test to a Gmail, an Outlook, and a Yahoo inbox shows you where you are actually landing. Placement in the Promotions tab is not the inbox, and it costs you replies. Small, steady adjustments keep reputation trending up instead of crashing after one aggressive week.

The full pre-send checklist

Here is the full sequence to run before every campaign. Print it, save it, or paste it into your team's launch doc.

1. Register dedicated outreach domains, separate from your primary domain.
2. Create two or three inboxes per domain and redirect each domain to your main site.
3. Publish SPF, DKIM, and DMARC on every sending domain and confirm all three pass.
4. Warm up each mailbox for two to three weeks, starting at 5 to 10 sends a day.
5. Cap warmed inboxes at 30 to 50 sends a day and scale with more mailboxes, not more volume.
6. Verify your list, remove invalids and duplicates, and keep the bounce rate under 2 percent.
7. Send a test to a seed inbox, check headers and placement, then launch.

Run this list before every campaign, not only the first. Domains age, DNS records get edited, and lists decay the moment you stop watching them. The teams with the best reply rates are rarely the ones with the cleverest copy. They are the ones whose technical foundation never lets them down. Ten minutes of checks protects months of hard-won sender reputation.