Check your domain (free)
The free check covers SPF (one record, under 10 DNS lookups), DMARC and MX. DKIM needs a selector name, so it's in the full check. Nothing here can see your spam rate or your email headers.
What Gmail and Yahoo require (their words)
From Google's Email sender guidelines and Yahoo's Sender Best Practices, both read on Nov 14, 2026.
Everyone sending to Gmail or Yahoo
Gmail: "Set up SPF or DKIM email authentication for your sending domains."
Gmail: "Keep spam rates reported in Postmaster Tools below 0.3%."
Yahoo: "Implement SPF or DKIM at a minimum" and "Keep your spam rate below 0.3%"
Bulk senders
Gmail: "If you send more than 5,000 messages per day to Gmail accounts, follow the Requirements for sending 5,000 or more messages per day." Those include: "Set up SPF and DKIM email authentication for your domain." "Set up DMARC email authentication for your sending domain. Your DMARC enforcement policy can be set to none." "Marketing messages and subscribed messages must support one-click unsubscribe, and include a clearly visible unsubscribe link in the message body."
Yahoo: "Implement both SPF & DKIM", "Publish a valid DMARC policy with at least p=none - DMARC must pass", "Implement a functioning list-unsubscribe header, which supports one-click unsubscribe for marketing and subscribed messages" and "Honor unsubscribes within 2 days"
The SPF 10-lookup limit is from the SPF standard, RFC 7208: "SPF implementations MUST limit the total number of those terms to 10 during SPF evaluation".
The full check: $12, one time
- DKIM check with key length. Enter the selector from one of your sent emails (or let it try common selector names) and see whether the key is at least 1024 bits, as Gmail and Yahoo require.
- Records to paste. A merged SPF record if you have more than one, a starter DMARC record with reports, and a step-by-step DMARC plan.
- Black Friday send plan built from Google's own guidance on volume and pacing.
- A 20-point pre-send checklist, with each requirement quoted and linked.
After you pay, you'll land on your check page. Bookmark it.
This checks public DNS records against published requirements. It can't guarantee inbox placement, and it doesn't see your sending reputation, spam rate or message content.
Why I made this
I'm Iggy, a software builder. Email authentication is three small DNS records that are easy to get subtly wrong, and the week before a big sale is a bad time to find out. This reads them for you and tells you plainly what's missing.