Will your sign-up emails reach the inbox?
Forty people sign up on launch day and none get their confirmation email. Check the three DNS records that decide whether your mail arrives, in seconds.
- SPF, DKIM, DMARC and MX in one check
- Plain-English fixes for each record
- Free, no sign-up
Why AI-built apps lose their emails
Most app builders and auth services come with a built-in email sender for testing. It works for your own sign-ups, so everything looks fine. It has tight sending limits and sends from a shared address, so on launch day the emails slow down, land in spam, or stop.
The fix is your own email provider (such as Resend, Postmark or SES) sending from your own domain, with three DNS records that prove the mail is really yours: SPF, DKIM and DMARC.
What each record does
SPF lists the services allowed to send as your domain.
DKIM signs each email, so receivers can tell it was not changed or forged.
DMARC tells receivers what to do when SPF and DKIM fail, and sends you reports.
- Add your domain in your email provider and copy the records it shows.
- Add them at your domain host (Cloudflare, Vercel, GoDaddy…).
- Add a DMARC record: start with v=DMARC1; p=none; rua=mailto:you@yourdomain.
- Run this check again, then send a real test to Gmail and Outlook.
Questions
- Why does my provider put SPF on a subdomain like send.example.com?
- Providers such as Resend and Amazon SES send bounces to a return-path subdomain and put the SPF record there. That is correct and passes the checks; this tool looks for it.
- It says no DKIM was found, but my provider says it is set up.
- DKIM records live under a selector name chosen by your provider, and some use names nobody can guess. If your provider's dashboard shows DKIM as verified, you are fine.
- Do I need DMARC?
- Gmail and Yahoo require it from bulk senders, and it stops others pretending to be you. Start with p=none to collect reports, then tighten to quarantine.