Deliverability insights
Page 13 of 15.
MCP Server for Deliverability: Run Inbox Checks From Your AI Agent
An official MCP server. Claude, GPT and any MCP-compatible agent can trigger placement tests, fetch results, and monitor a domain directly.
A2A Ready: Inbox Check Is Built for Agent Workflows
Both MCP and A2A are first-class. Your agents can call Inbox Check tools, subscribe to results, and chain placement-testing into longer plans.
Free Domain Monitoring: DNS, MX, Blacklist, Auth — Watched Daily
Daily checks on SPF, DKIM, DMARC, PTR, MX, A records and major blacklists. Free alerts when anything changes.
Free Presend Spam Analysis: Score Your Cold Email Before You Hit Send
Three-tier analyzer: stop-words and domain intel, AI human-perception pass, and link intelligence. A 5-second check that catches most spam triggers before they ship.
Per-Provider Spam Scoring: Gmail, Outlook, Yandex, Mail.ru Separately
Aggregate "spam score" numbers lie. Providers weight triggers differently. We score your draft per-provider with specific reasons.
Gmail Folder Detection: Primary, Promotions, Updates, Social, or Spam
Gmail has four inbox tabs and the folder matters. We detect the exact folder your email lands in — free.
Post-Send Email Tracking: Get Alerted If Your Mail Moves to Spam
Filters reclassify mail hours or days later. We keep watching after the send and alert you the moment a provider moves your message.
4,000+ Real Seed Mailboxes, 30+ Providers, Zero Dollars
Where our seed network lives, how we keep mailboxes fresh, and why 4,000+ seeds across 30+ providers produces more realistic placement numbers.
100,000 Placement Tests Per Day on the Free Tier
Capacity we actually hit. How we run the infrastructure, what the hard limits are, and why rate limits worth worrying about live elsewhere.
Inbox Check vs GlockApps, MXToolbox, Mail-Tester: Honest Comparison
Feature-by-feature comparison with the three most common alternatives. Pricing, seeds, provider coverage, API, folder detection and agent support.
How We Afford to Give Inbox Check Away
The honest business model. What the paid tier actually covers, what offsets free-tier costs, and why free-forever is sustainable.
Free Placement Test API: No Signup, OAuth for Zapier/Make/n8n
A public HTTP API for placement testing. Call anonymously within rate limits, or authenticate via OAuth for higher concurrency and long retention.
Why Our Seed Network Sits Outside Every Warmup Pool
A placement test that uses pool-resident mailboxes grades itself. Here is how we keep the seed network independent and why it matters.
Russian and CIS Inbox Testing Free: Mail.ru, Yandex, Rambler, List.ru
CIS inboxes are a separate filter stack that most Western tools ignore. We seed all of them and test placement for free.
Complete Microsoft Coverage: Outlook.com, Hotmail, Live, Office 365
Microsoft runs at least four overlapping mail systems with different filter stacks. We seed all of them separately.
Gmail Personal vs Google Workspace: The Hidden Placement Divide
The same message can land Primary on consumer Gmail and Junk on a Workspace tenant. Why the two Gmails filter differently.
Per-Seed Placement Detail: Not Just a Percentage — See Every Mailbox
Competitors report 'Gmail: 72%'. We report every seed mailbox, its folder, its auth verdict, and the raw headers.
Authentication Audit + Placement Test in One Free Report
SPF, DKIM, DMARC, BIMI, MTA-STS, PTR — all validated. Placement across 30+ providers. Both halves of the deliverability picture in one report.
Inbox Check for Agencies: Multi-Client Monitoring, Free Tier That Scales
Agencies managing outbound for multiple clients can monitor them all on the free tier. Tagging, per-client dashboards, API, webhooks — no per-seat fees.
OAuth for Zapier, Make, n8n: Placement Tests in Your Automation Stack
Standard OAuth 2.0 lets Zapier, Make, n8n and any automation tool call Inbox Check natively. Triggers, actions, real authentication. Free.
No Signup, No Credit Card: A Placement Test in 30 Seconds
We don't ask for your email to run a placement test. Paste the draft, pick providers, go. The anti-friction policy and why we chose it.
iCloud, GMX, Web.de, Zoho, ProtonMail: We Cover the Long Tail
Most tools cover Gmail and Outlook well and leave everyone else as a footnote. We test iCloud, ProtonMail, GMX, Web.de, Zoho and more.
We Screenshot Your Email Across Providers: Catch Layout Bugs Before Customers Do
Every Inbox Check run captures rendered screenshots across providers. See exactly how your email looks in Gmail, Outlook, Yahoo, Mail.ru before the customer sees a broken layout.
Gmail vs Outlook Rendering Differences: Our Screenshots Show You Both
Gmail and Outlook render HTML email very differently. Side-by-side screenshots expose the most common breakage points.
Dark Mode Email Rendering: Screenshot Every Provider, Free
Dark mode is where a third of email users live and where half of templates look broken. Our screenshots capture both light and dark variants per provider.
Mobile vs Desktop Email Layout: Our Screenshots Cover Both
60-70% of email is opened on mobile. 100% of design review happens on desktop. The gap is where campaigns break. We render both viewports per provider.
Email Screenshot API: Automate Visual Regression Testing of Every Campaign
Pipe email screenshots into your CI. Any template edit gets diffed against the last known good. Broken layouts caught before the campaign runs.
Why We Don't Do Warmup (And Never Will)
A manifesto. Warmup pools were a 2020 answer to a 2018 problem, and in 2026 they are a fingerprint filters can see. We refuse to add one — here is why.
What Gmail Actually Thinks About Warmup Networks
From public Gmail sender guidelines, ML research on coordinated behaviour, and placement-test data: how Gmail models warmup pools today and what that means for your placement.
We Spent $3,600 on Folderly. Here's What We Learned
A six-month case study of a paid warmup engagement. Raw placement numbers, dashboard vs independent tests, and the non-obvious lessons from reading the delta.
Real Warmup for Cold Email: The No-Bullshit Guide
What actually moves placement for a new domain: auth, verification, ramp discipline, content, monitoring. A 28-day playbook with no pool and no subscription.
How Google's ML Fingerprints Warmup Pools
Six signals every major provider can use to detect warmup pools: graph closure, template uniformity, reply latency, diurnal patterns, engagement co-occurrence, domain age.
Synthetic Engagement Signals Google Stopped Counting in 2026
What Gmail used to count that it now mostly doesn't — opens, synthetic replies, pool mark-as-important, tracking-pixel fires. And what it's counting instead.
Your Warmup Dashboard Says 95%. A Real Placement Test Says 40%
Why warmup tools report stellar inbox numbers that independent placement tests cannot reproduce. The measurement loop and how to audit your own tool in 30 minutes.
The 48-Hour Warmup Kill Test: Is Your Tool Doing Anything?
A 48-hour experiment any team can run. Pause warmup, measure real placement, compare to baseline. The cheapest audit before paying for another month.
Lemwarm vs Mailivery vs Warmbox: A Technical Teardown
Three popular warmup tools, what each actually does to your domain, and where their claims and reality diverge — based on traffic captures and 8 weeks of measurement.
9 Questions to Ask Before Buying a Warmup Subscription
A buyer-side checklist to separate warmup vendors whose pool is actually doing something from those whose dashboard just grades itself.
Ramping a New Domain to Real Prospects Without Any Warmup Tool
A 28-day ramp schedule to real cold prospects — no pool, no dashboard theatre. Volume curve, segmentation, checkpoints and what to monitor each week.
List Verification Before Warmup: The Priority Nobody Argues Against
Bounce rate has a bigger impact on placement than any warmup pool ever will. A checklist and verification stack that beats 6 weeks of warmup.
A/B Testing Cold Email Content Beats Warmup Volume Every Time
Subject line, first line, CTA, length — each variable alone moves placement more than a month of warmup pool traffic. What to test and how to measure it.