Deliverability insights
Honest, practical writing on inbox placement, authentication, and the tools that actually matter. No fluff, no SEO padding.
Explore 50 competitor and tool comparisons in five languages →
Email infrastructure of the Tranco top-1M domains — MX, SPF, DMARC
A daily census of the world's most-visited 1 million domains measuring real-world email deliverability infrastructure: which mail providers dominate (Google Workspace, Microsoft 365, Yandex, Mail.ru, Zoho, self-hosted), how SPF policies are configured at the apex, DMARC enforcement levels (none / quarantine / reject) via the _dmarc record, plus NS delegation and A/AAAA/CAA presence. Open data for deliverability researchers, ESP product teams, and security analysts comparing their own setup against industry baselines.
- Domains scanned
- 1,000,000
- MX providers
- 200+
- Auth signals
- SPF · DMARC
- Refresh
- Daily
How to cite: Live Direct Marketing, "Email infrastructure of the Tranco top-1M domains," check.live-direct-marketing.online/email-stats, snapshot date as shown on the page.
Amazon SES Mailbox Simulator vs. a Real Inbox Placement Test
Learn what the Amazon SES mailbox simulator proves, when a real seed test is possible, and how to check observed placement with LDM.
SendGrid Sandbox Mode vs. a Real Inbox Placement Test
Separate SendGrid API validation from actual email delivery, then run a controlled LDM test through the route your application really uses.
Mailgun Test Mode vs. Real Delivery: Checking Inbox Placement with LDM
Understand why Mailgun o:testmode cannot measure mailbox placement, then prepare a representative live test with useful diagnostic evidence.
Postmark Message Streams: Test the Route Your Email Actually Uses
Choose the correct Postmark Message Stream for a real LDM test, preserve API or SMTP routing, and interpret the observed mailbox results.
What a Seed Panel Can and Cannot Represent
A seed panel represents the controlled mailboxes actually available and observed during a test.
Why Inbox Placement Varies by Receiving Provider
Different receiving providers can place the same campaign in different folders because they operate different filtering systems, policies, account histories, and receiving infrastructures.
The Five Identities Behind an Email Sender
An email has several sender identities: the visible From address, the SMTP envelope sender, the DKIM signing domain, the connecting sending IP, and the domains used in links.
Why Authentication Passes Do Not Guarantee Inbox Placement
SPF, DKIM, and DMARC answer questions about authorization, signatures, and domain alignment.
How Mailbox Filtering Combines Signals
Mailbox filtering can combine authentication, infrastructure, reputation, message content, sending behaviour, and recipient-specific information.
Why a Spam Score Is Not an Inbox Prediction
A spam score is an assessment produced by a particular scanner using its own rules and inputs.
What Makes a Placement Test Representative of Production
A representative placement test reproduces the sending route and message you intend to use in production closely enough to answer a stated question.
Why Forwarding an Email Changes the Test
Forwarding introduces an additional mail flow.
Email Not Found Is a Distinct Diagnostic Result
A not-found result means a successful mailbox check did not find a matching copy at that observation time.
Unknown, Pending and Failed: The Evidence States in a Report
Pending describes unfinished work.
What 24-Hour Folder Monitoring Actually Observes
Folder monitoring follows an already detected copy over time.
Why One Passing Test Cannot Approve an Entire Campaign
One successful placement test describes the controlled copies, route, content, and observation stage used in that run.
Domain, IP and URL Reputation Are Different Objects
Domain reputation, sending-IP reputation, and URL reputation concern different objects.
Authentication, Reputation and Engagement: Three Separate Questions
Authentication asks whether a message's domain use and signature validate.
Transactional and Marketing Email Need Different Success Criteria
A transactional notification succeeds when it performs its intended user task reliably and safely.
Volume, Cadence and Bursts: Three Dimensions of Sending
Volume is how much mail is sent over a stated period.
What Complaints and Feedback Loops Tell a Sender
A complaint is evidence that a recipient or receiving system reported a message as unwanted under a defined process.
Consent and Inbox Placement Answer Different Questions
Consent or another applicable permission basis concerns whether and how you may contact a person.
Spam Traps: What a Placement Test Cannot Detect
A placement test does not audit an entire address list for spam traps.
Rejected, Deferred and Placed in Spam Are Different Outcomes
Rejection, deferral, and Spam placement occur at different stages and need different evidence.
Domain, Subdomain and Organizational Domain in Email
A domain name, one of its subdomains, and the organizational domain used for authentication policy are related but distinct concepts.
From Single Tests to a Placement Trend
A placement trend is a sequence of comparable observations with documented sending conditions, provider coverage, and timing.
How to Evaluate an Inbox Placement Testing Service
Evaluate a placement service by the observations it can substantiate, the limits it makes visible, and how well its workflow matches your sending question.
Placement, Rendering and Accessibility Require Separate Checks
Placement asks where a received copy was observed.
A Plain-Language Glossary for Inbox Placement Reports
A placement report becomes easier to use when each term names one observable stage or technical object.
Instantly: Preview, Test Send and Observed Placement
Instantly's preview, a test send and an observed mailbox folder answer three different questions.
lemlist: Test Fully Rendered Personalization
Test the message after lemlist has substituted personalization, including the signature, custom text and destination URLs.
Reply.io: Compare the First Email and a Follow-Up
Compare a Reply.io opening email and follow-up as separate messages, keeping the sender and recipient panel controlled.
Mailshake: Compare Tracked Links in a Controlled Placement Test
To investigate links in a Mailshake message, compare the same sender and message with one documented link-setting change.
Woodpecker: Compare Two Senders on One Domain
Two Woodpecker mailboxes on the same domain are not interchangeable test subjects.
Apollo: Test the Final Signature and Calendar Links
An Apollo placement test should include the signature and calendar URL that the chosen mailbox actually appends.
Saleshandy: Separate Sender and Content Variables
To investigate a Saleshandy placement difference, change the sender or the content in a comparison, not both at once.
Snov.io: Retest After a Domain Configuration Change
After changing a domain setting used by Snov.io, verify the live configuration and send a fresh original message through the same account route.
QuickMail: Compare a Short Message with a Calendar-Link Variant
To test whether a calendar-link version behaves differently from a short QuickMail message, keep the sender and core text stable and change only the optional scheduling element.
Mailchimp: Check Personalization Beyond the Test Email Preview
A Mailchimp test email does not fully populate contact-specific merge tags or reproduce live tracking.
Brevo: Validate Event Data in a Real Transactional Email
To verify a Brevo transactional message, test the event data that your application actually submits and inspect the rendered received copy.