Free email and SMS tools
No sign-up. They run in your browser.
Domain grade
SPF, DKIM, DMARC and MX in one pass.
SPF
Every include and lookup, counted.
DMARC
What receivers do with a forgery.
DKIM
The key that signs your mail.
DMARC record
Build one, then publish it.
Headers
Find the check that failed.
SMTP codes
When to retry, when to stop.
SMS segments
How many parts a text costs.
About these tools
Are these tools free?
Yes, with no account. The DNS checks run from your browser against a public DNS-over-HTTPS resolver, and the header analyzer and calculators never send what you type anywhere.
Which check should I run first?
The domain grade. It reads SPF, DKIM, DMARC and MX in one pass and links each problem to the tool that explains it.
Why does my domain pass here but mail still lands in spam?
DNS is the part of deliverability anyone can see. Receivers also weigh sending reputation, complaints and content, which no lookup shows. Paste a delivered message's headers into the header analyzer to see what the receiver decided.
Free tools
Send from a domain that checks out
Unitpost sets up SPF, DKIM and DMARC with you and keeps checking them.