Deliverability insights
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Free Inbox Placement Test: What GlockApps Charges $59/mo For
A straight answer to "do I need GlockApps?". What a placement test actually produces, and how to get the same output free with 20+ providers.
UniSender and SendPulse Deliverability: Free Test for CIS Senders
UniSender and SendPulse dominate the CIS market, but their own dashboards hide placement data. How to test Mail.ru and Yandex placement for free.
Klaviyo Email Deliverability: Free Test for E-commerce Senders
Klaviyo's "Delivered" rate is almost meaningless for Gmail Promotions. The pre-send routine that tells you whether your flow lands in Primary.
ConvertKit (Kit) Email Deliverability: Are Your Newsletters Hitting Inbox?
Kit's shared-IP reputation shifts constantly. How creators can run a placement test before every broadcast, and which setting fixes 60% of cases.
ActiveCampaign Deliverability: Free Inbox Placement Check
ActiveCampaign's "Delivery Rate" is not inbox placement. The quick test that shows you what their dashboard hides — plus the three settings to audit.
Brevo (Sendinblue) Deliverability Test: Free Alternative to GlockApps
Brevo sends from its own IPs — good for transactional, rough for marketing. The free pre-send test that catches shared-pool reputation hits.
HubSpot Emails Going to Spam: How to Diagnose and Fix
HubSpot-specific spam issues: shared tracking domain, "via hubspot.com", poorly warmed sending domains. The fix list for each.
Woodpecker Email Deliverability: Test Across 20+ Providers Free
Woodpecker's Inbox Ninja is bundled but limited. A free 20+ provider placement test you can run before every sequence launch.
Smartlead Deliverability: Free Inbox Test Before Your Campaign
Smartlead's unified inbox rotation is powerful — but it hides per-account placement. The pre-campaign check that tells you which inbox is burning.
Apollo.io Emails Going to Spam: How to Check and Fix (2026)
Apollo's shared sending pool moves in and out of Spamhaus SBL. How to test your real placement and the three settings that pull you back into Inbox.
Instantly Deliverability: What Their Dashboard Does Not Show You
Instantly shows warm-up progress and sends — but not per-provider placement. The three gaps in their dashboard and how to fill them for free.
Lemlist Deliverability Dropped? Free Inbox Placement Test to Find Out Why
If Lemlist suddenly lands in Spam across your sequence, it is almost always one of four causes. How to diagnose each in under 10 minutes.
Postmark vs SendGrid vs Amazon SES: Which Lands in Inbox? (We Tested)
We ran identical messages through Postmark, SendGrid and SES. Inbox rates, spam rates and what to expect on a shared pool vs dedicated IP.
Amazon SES Inbox Placement: Free Test Before You Scale
SES is cheap and powerful — until your shared pool gets a bad neighbour. How to run a free placement test before requesting your production limit.
SendGrid Deliverability Issues: How to Diagnose Before Paying for GlockApps
SendGrid's own reports stop at "Delivered". A free 10-minute diagnostic flow that tells you which shared pool you are on and where you actually land.
Mailchimp Emails Going to Spam? Test Your Placement Free Before Sending
Mailchimp's shared pool reputation shifts weekly. A free placement test to run before every campaign — before Mailchimp's own reports catch up.
Zoho Mail, Fastmail, HEY: Deliverability to Privacy-First Providers
Small audience, spiky filtering. How to get into Zoho, Fastmail and HEY inboxes — and what these three score differently from Gmail.
iCloud Mail Deliverability: Why Apple Users Do Not See Your Email
iCloud is 15% of US inboxes and almost no placement tool covers it. The three things iCloud punishes harder than Gmail — and the fix for each.
ProtonMail Deliverability: Does Your Email Even Get Through?
ProtonMail users are high-value and hard to reach. The ProtonMail-specific filtering quirks and how to validate placement before you send at scale.
WP.pl and Onet.pl: Email Deliverability for the Polish Market
Poland's two biggest ISPs have their own postmaster tools, their own blacklists, and their own quirks. A sender's guide nobody else publishes.
Orange, LaPoste, Free.fr: Email Deliverability for the French Market
Gmail tests are useless for a French B2C audience. How Orange, LaPoste and Free.fr filter mail — and what to verify before you ship a French campaign.
GMX and T-Online Email Deliverability: Guide for the German Market
Germany sits on GMX, Web.de and T-Online. Their filtering rules, their postmaster portals, and the authentication strictness nobody warns you about.
Cold Email to Russian Companies: Gmail vs Mail.ru vs Yandex Placement
Same message, three ISPs, wildly different results. The data behind cold-email placement in Russia and what it means for your sequence.
SPF and DKIM for Mail.ru: Step-by-Step Setup Guide
Mail.ru's postmaster is stricter than Gmail on DKIM selector length and SPF. The exact DNS records and a walkthrough of postmaster.mail.ru.
How to Test Inbox Placement for Russian Email Providers (Free)
Mail.ru, Yandex, Rambler, List.ru — four providers, four different filtering stacks. A single test that covers all of them for free.
Rambler Mail Deliverability: What Senders Need to Know
Rambler is tiny but stubborn: 4% of Russian inboxes and its own filter. The specifics of getting mail through Rambler's Spam folder.
10 Key Differentiators: Why Inbox Check Isn't Another Deliverability Tool
Free forever, 4000+ seeds, 30+ providers, MCP and A2A, folder detection, post-send tracking, presend analyzer, domain monitoring, no signup, 100K tests/day.
Inbox Check Is Free Forever: Unlimited Placement Tests, No Credit Card
No freemium, no signup wall, no hidden credit-card. Why our core placement-testing product is free forever and what that means for teams that use it.
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.