20 guides

Cold Email Deliverability: The Complete Guide

Authentication, warm-up, sending limits, spam complaints and domain reputation, with the numbers from 34,973 tracked sends.

Deliverability is the only part of outbound where the rules are set by someone else. Google, Microsoft and Yahoo decide whether your message reaches an inbox, and they publish most of what they expect.

Across 34,973 tracked sends inside Getlead we held bounce at 0.51% and stayed under the 0.3% spam complaint ceiling the mailbox providers enforce. Neither number came from a clever trick. Both came from authentication, gradual volume, and refusing to send to addresses that had not been verified that week.

The guides below cover that stack in the order it breaks: authentication first, then domain and mailbox setup, then volume, then the signals that decide whether a healthy setup stays healthy.

Or start from mailboxes that are already warmFour to six weeks of warmup run before you order, the day by day log handed over with the credentials, and the domain registered in your name. From $29 a month for three mailboxes and a domain.See pre-warmed mailboxes

Every guide in this cluster

Start with authentication if you are setting up, or with the audit guide if mail that used to land has started disappearing.

10 Best Pre-Warmed Email Account Providers Compared (2026)What ten pre-warmed mailbox providers actually publish: price, warmup length and who keeps the domain. Six cost less than us. One will not transfer ownership. 11 min read Spam Complaint Rate: The One Metric That Ends Cold Email ProgramsThree complaints per thousand emails puts you at the ceiling. How the rate is calculated, where to see it, and the levers that actually move it down. 10 min read Gmail, Yahoo and Microsoft Sender Requirements: The 2026 ChecklistAuthentication, the 0.3% spam ceiling and one click unsubscribe, in implementation order, with the rejection codes you get when you skip one. 10 min read Why Cold Emails Land in Spam: A Diagnostic Order of OperationsWork the causes in the order they actually break: authentication, then domain history, then list quality, then content. Most teams start at the wrong end. 11 min read Dedicated Sending Domains: How to Set Them Up Without Wrecking Your Main OneWhy cold outbound never runs from your primary domain, how many sending domains you need, and the naming, DNS and warm-up sequence that keeps them clean. 10 min read Cold Email Sending Limits: What Providers Allow vs What Is Actually SafeGoogle allows 2,000 a day and Microsoft 10,000 recipients. Neither number is a cold email plan. Here is the safe volume per mailbox and the math behind it. 10 min read Mailbox Rotation: Spreading Cold Email Volume Without Looking Like a BotHow rotation distributes sends across mailboxes and domains, the ratios that hold up, and the three ways teams implement it badly. 10 min read DMARC Policy: Going From p=none to p=reject Without Losing MailWhat each DMARC policy does, how to read aggregate reports, and the staged rollout that gets you to enforcement without blocking legitimate email. 10 min read Soft Bounce vs Hard Bounce: Reading the Codes and Acting on ThemWhat 4xx and 5xx responses mean, which bounces to suppress immediately, which to retry, and the thresholds that separate a bad list from a bad setup. 10 min read The Unsubscribe Link Is a Deliverability Feature, Not a Legal ChoreOne click unsubscribe, the 48 hour and 10 day rules, and why hiding the opt-out costs more deliverability than the contacts it saves. 10 min read Email Blacklists: How You Get On One and What Actually Removes YouWhich blocklists matter, how to check whether you are listed, the delisting process for each type, and the sending behaviour that got you there. 10 min read A Cold Email Deliverability Audit You Can Run in One AfternoonTwenty checks across authentication, domain, list and sending behaviour, in the order that finds the cause fastest, with the numbers to compare against. 11 min read The Cold Email Ramp-Up Schedule: Week by Week to Full VolumeA four week warm-up plan with daily volumes, what to watch at each stage, and the signals that mean stop rather than continue. 10 min read Gmail vs Outlook Deliverability: Two Filters, Two Sets of RulesWhy the same campaign lands in one inbox and the spam folder in another, what each provider weighs, and how to diagnose them separately. 10 min read Sender Reputation Monitoring: The Four Dashboards Worth CheckingPostmaster Tools, SNDS, DMARC reports and your own reply data. What each one reveals, how often to look, and the thresholds that mean act now. 10 min read Email Bounce Rate: What's Acceptable & How to Fix It (2026)Hard vs soft bounces, the thresholds that trigger spam-foldering, and the exact playbook to get your email bounce rate under 2% and keep it there. 9 min read How Many Inboxes and Domains Do You Need for Cold Email?Calculate cold email inbox and domain capacity from monthly prospects, sequence steps, sending days, reserve capacity and ramp assumptions. 11 min read How to Warm Up an Email Domain: The 2-Week Plan (2026)A day-by-day email domain warm-up plan for 2026: volumes, the engagement signals that matter, automation options, and the mistakes that restart the clock. 11 min read SPF, DKIM & DMARC Explained in Plain English (2026 Guide)What SPF, DKIM and DMARC actually do, why Gmail and Yahoo require them, and the exact records to publish, explained without jargon in one guide. 11 min read Cold Email Deliverability in 2026: Land in the InboxWhy cold emails go to spam and how to fix it: SPF/DKIM/DMARC, warm-up, verification, volume ramping and copy patterns that survive Gmail's 2026 filters. 10 min read

Frequently asked

What is the single biggest deliverability factor?

List quality. Authentication and warm-up are prerequisites, but the fastest way to lose an inbox is sending to invalid addresses. In our verification of 383,368 raw B2B addresses, 23.9% were invalid, and sending to that share produces bounce rates no warm-up schedule can offset.

How long does email warm-up take?

Two to four weeks for a new domain before meaningful volume, ramped gradually rather than jumped. The ramp-up schedule guide sets out the daily increments and the signals that say you moved too fast.

What complaint rate is safe?

Below 0.1% in practice, with 0.3% as the ceiling the major providers publish. Complaint rate is measured on delivered messages, so it rises when your list quality falls even if your content never changes.

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