All 10 Checks Explained
Every check we run, what it means, and how to fix it when it's not passing. No jargon — or at least, every bit of jargon explained.
1. SPF
What it is: a DNS record listing which servers are allowed to send email for your domain. Receivers check the connecting server against that list.
When it fails: your sending server isn't in the list — often because you started sending through a new SMTP provider and never added its include: to your SPF record.
Fix: add your provider's include (e.g. include:spf.brevo.com) to the v=spf1 TXT record on the sending domain. One record only — multiple SPF records are themselves an error.
2. Sending-Domain Alignment (SPF root)
What it is: a WordPress-specific check most generic tools miss. Your From address says one domain, but the email may technically be sent via a subdomain or your email provider's own domain.
Important: sending through a provider domain (Brevo, Mailgun's mg. subdomain, etc.) is normal and healthy — as long as DKIM aligns with your From domain, DMARC passes and we show this as a pass. We only warn when neither SPF coverage nor DKIM alignment exists, which genuinely breaks DMARC.
3. DKIM
What it is: a cryptographic signature on every email, verified against a public key in your DNS. Proves the email wasn't forged or altered.
Special case — "DKIM Record Problem": if your email IS signed but receivers can't read the key record (a permerror), the usual cause is a duplicated or truncated DKIM TXT record in DNS. Your provider's dashboard can say "verified" while strict receivers still fail it. Our report diagnoses the exact record when this happens.
Fix: add the DKIM record from your email provider exactly as given; delete duplicates; re-copy if truncated.
4. DMARC
What it is: the policy that tells receivers what to do with email that fails SPF/DKIM — nothing (p=none), spam-folder it (p=quarantine), or reject it (p=reject).
Why p=none is a warning: it means "monitor only" — you get no protection against spoofing, and Gmail/Yahoo increasingly expect enforcement. It's the right starting point, but move to p=quarantine once SPF and DKIM pass consistently.
5. Spam Filter Check (SpamAssassin)
What it is: we run your actual email through SpamAssassin — the real spam filter used by mail servers worldwide — and show you every rule it triggered, with points. Lower is better; 5.0 or above means spam filters will likely catch you.
Reading the rule table: green negative points help you (good reputation, valid DKIM); red positive points hurt (HTML-only email, missing headers, image-heavy content). Fix the biggest red items first.
6. Blacklists (manual)
What it is: your sending IP and domain checked against 23 major blacklists (Spamhaus, SpamCop, Barracuda, SURBL and more). Run it with the button on your report.
If you're listed: each blacklist has its own delisting process — search "[blacklist name] delist". Note that some listings (like Spamhaus PBL) are normal for shared hosting and don't count against you.
7. Reverse DNS (PTR)
What it is: your sending IP should resolve back to a hostname, and that hostname should resolve forward to the same IP. Gmail and Outlook penalise or reject servers without this.
Fix: if you send through a provider (Resend, Brevo, etc.) this is handled for you. If self-hosting, ask your host to set the PTR record.
8. MX Records
What it is: the DNS records that let your domain receive email. Not directly about sending — but domains that can't receive mail look suspicious to filters, and your customers can't reply to you.
9. Email Headers
What it checks: structural problems in the email itself — most commonly an HTML email with no plain-text alternative, which some filters penalise. Fixed in your email template or sending plugin settings.
10. List-Unsubscribe & Content Quality
List-Unsubscribe: required by Gmail and Yahoo for bulk senders since 2024. Transactional email (receipts, password resets) doesn't need it — so a missing header there is informational, not a problem.
Content quality: we scan the email body for images missing alt text, dangerous HTML (scripts, iframes), URL shorteners (a spam signal), image-heavy/low-text composition, and oversized HTML (Gmail clips messages over ~102 KB).