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Free bulk mail check. Against the Google and Yahoo rules.

Paste the headers of a message you sent. We grade it against the Google and Yahoo bulk sender rules, and Microsoft's, then check the DNS records behind them.

kanbello.xyzViolates the requirements
  • From alignment as actually sentPass
  • One-click unsubscribe (RFC 8058)Fails
  • Unsubscribe headers covered by DKIMAt risk
  • Message format basics (RFC 5322)Pass
  • Functional unsubscribe (Microsoft)Pass
  • DMARC policy publishedPass
  • SPF record publishedPass
  • DKIM signing key in DNSFails
A made-up newsletter, graded by the real checker.

What we read. And what one message cannot show.

The headers you paste, three records from public DNS, and nothing about your mail over time.

Read

The headers you paste List-Unsubscribe-Post

Alignment as the receiver reported it, one-click unsubscribe, whether DKIM signs the unsubscribe headers, and the basic message format. The grader is the one behind the product’s Mandate tab. Up to 64 KB.

Looked up

Three DNS records _dmarc, SPF, DKIM key

The From domain’s DMARC policy and SPF record, and the DKIM key the message’s signature names, read from public DNS when you run the check.

Not read

Your mail over time Gmail spam rate

Your Gmail spam rate and whether Microsoft is already refusing your mail only show over time. Mandate Monitor joins both, and comes with the Lite plan.

Questions. Short answers.

Who the rules bind, what each check means, and what one message leaves out.

Who has to follow these rules?

Google and Yahoo apply them to bulk senders: roughly 5,000 messages a day or more to their users. Microsoft holds senders to similar rules at Outlook.com. Every sender needs SPF or DKIM; bulk senders need both, plus DMARC and one-click unsubscribe.

What is one-click unsubscribe?

A List-Unsubscribe header with an HTTPS address, plus List-Unsubscribe-Post: List-Unsubscribe=One-Click, so a mail app can unsubscribe someone in one step. One-click unsubscribe (RFC 8058), explained.

Bulk or transactional?

The unsubscribe rules bind bulk and marketing mail, not receipts or password resets. Detect reads the message: a List-Unsubscribe or Precedence: bulk header makes it bulk. A skipped check reads Skipped, never Pass.

What can one message not show?

Your Gmail spam rate, which Google wants below 0.1% and never at 0.3%, and whether Microsoft is already refusing your mail. Both need data over time. Google Postmaster Tools: Gmail's own verdict on your mail.

Do you keep what I paste?

No. We read three DNS records for the From domain and keep nothing. We count that the tool ran and which verdict it gave, so we can see what people run into.

How many can I run?

Ten an hour from one network. The limit keeps the tool fast for everyone.

Go further. Guides and the other tools.

The reading behind each finding, and the checks this page leaves to a sibling tool.