Free email deliverability checker
Why is your email going to spam?
Check your domain's SPF, DKIM and DMARC in seconds and get the exact fix. Built for the Gmail & Yahoo bulk-sender rules. No signup — runs in your browser.
What it checks
- SPF — one valid record, an enforcing policy, and a real recursive count of DNS lookups against the 10-lookup PermError limit.
- DKIM — a public key for your selector (we probe common ones automatically) and a key-length warning.
- DMARC — a policy that's actually enforcing, with reports collected. Gmail/Yahoo require this for bulk senders.
- MX — are mail exchangers published correctly?
- MTA-STS, TLS-RPT, BIMI — the advanced records most checkers skip.
More free tools
- Record explainer
Paste a DMARC or SPF record → plain-English, tag-by-tag breakdown.
- Email header analyzer
Paste raw headers → SPF/DKIM/DMARC results + delivery path.
- DMARC generator
Build a valid DMARC record to publish.
Fix email deliverability without guessing
When Gmail and Yahoo tightened their bulk-sender rules in 2024, weak email authentication stopped being a minor issue and started sending real mail to spam. Spamcheck runs the same checks a receiving server does — SPF, DKIM, DMARC, MX, MTA-STS, TLS-RPT and BIMI — straight from your browser, and tells you exactly which record is wrong and how to fix it. No signup, no sending a test email, nothing stored.
Unlike most checkers, the SPF test does a real recursive count of your
DNS lookups, so it catches the silent PermError that breaks SPF once you
pass ten lookups. Pair it with the record explainer to
understand any record, and the guides to fix the underlying cause.
Frequently asked questions
Why are my emails going to spam?
Almost always a technical authentication problem: a missing or misconfigured SPF, DKIM or DMARC record, an unaligned Return-Path, a new domain with no reputation, or a high spam-complaint rate. Run the checker to see which applies to your domain.
How do I fix SPF, DKIM and DMARC?
Publish one SPF TXT record ending in ~all or -all, add the DKIM key your email provider gives you, and add a DMARC record at _dmarc.yourdomain.com starting at p=none. Then move DMARC to quarantine and reject. The checker tells you exactly what is missing.
Is Spamcheck free?
Yes, completely free with no signup. The checker, record explainer, header analyzer and DMARC generator are all free.
Do you store the domains I check?
No. All checks run in your browser using DNS-over-HTTPS. Nothing you enter is sent to or stored on our servers.
What do Gmail and Yahoo require for bulk senders?
Valid SPF and DKIM, a published DMARC policy, an aligned From domain, one-click unsubscribe, and a spam-complaint rate under 0.3%.
Latest guides
- DKIM Not Signing? How to Diagnose and Fix Missing or Failing DKIM
DKIM shows none or fail in DMARC reports — the common causes (wrong selector, expired key, missing record) and how to fix each.
- DMARC p=none → p=reject: A Safe Step-by-Step Migration
How to move DMARC from monitoring (p=none) to enforcement (p=reject) without blocking your own legitimate email.
- How to Fix SPF Softfail — Why DMARC Fails Even When SPF Passes
SPF softfail (~all) and the alignment trap: why DMARC still fails when SPF passes, and the Return-Path fix that actually solves it.
- Gmail & Yahoo Bulk Sender Requirements, Explained (2026)
What the 2024 Gmail and Yahoo sender rules actually require — SPF, DKIM, DMARC, one-click unsubscribe, and spam-rate limits — in plain English.
- How Long to Warm Up a New Email Domain? (Cold-Email Ramp Schedule)
A concrete 4–8 week warm-up schedule for a new sending domain, with daily volume targets and the reputation rules that matter.
- Set Up SPF, DKIM & DMARC for Google Workspace (Step-by-Step)
Exact DNS records to authenticate email for Google Workspace — SPF, DKIM (2048-bit), and DMARC — copy-paste ready.
- Set Up SPF, DKIM & DMARC for Microsoft 365 / Outlook
Authenticate email for Microsoft 365 — the SPF record, the two DKIM CNAMEs (not TXT), and DMARC — with exact values.
- Fix 'SPF PermError: Too Many DNS Lookups' (the 10-Lookup Limit)
SPF allows only 10 DNS lookups. Go over and SPF returns PermError and fails. Here's how to count yours and flatten the record.
- SPF vs DKIM vs DMARC: What Each One Actually Does
A plain-English breakdown of SPF, DKIM and DMARC — what each record proves, how they work together, and what to publish.
- What Is a DMARC Record? Every Tag Explained (p, rua, pct, sp, aspf, adkim)
A plain-English reference for every DMARC tag — what each one does, valid values, and what to set.
- Why Your Emails Go to Spam — and How to Fix It (2026)
The technical reasons email lands in spam — SPF, DKIM, DMARC, reputation — and a step-by-step fix for each.