Email Spam Checker
Check a message before you send it
Tool features
4 checks
Bulk sender rules
One-click unsubscribe, List-Unsubscribe-Post and a visible opt-out — what Gmail, Yahoo and Microsoft now require from bulk mail
Rendering and weight
Plain-text alternative, Gmail’s 102 KB clipping threshold, image-to-text balance, alt text and stripped active content
Link audit
Shorteners, bare IP addresses, punycode hosts, plain http:// and link text that names a destination the href does not go to
Facts, not folklore
No spam-word scoring. Every finding is something measurable in the message that you can verify and change
What is an email spam checker & how it works
A spam checker looks at the message itself rather than the domain that sends it. Mailbox providers score both: the sending domain's authentication and reputation, and what the message carries — its headers, its structure, where its links go and how its subject line reads.
This tool covers the second half. It parses the pasted message, walks its MIME parts and measures the signals filters act on: the one-click unsubscribe headers Gmail, Yahoo and Microsoft require from bulk senders, HTML past Gmail's 102 KB clipping point, image-only layouts, hidden text, link text that disagrees with its destination, and subject-line tricks. It does not score “spam words” — every finding is a fact about the message you can verify and change.
List-Unsubscribe-Post
The RFC 8058 header that turns an unsubscribe link into the one-click button mailbox providers show.
multipart/alternative
A message carrying both HTML and plain-text versions of the same content.
Preheader
A short hidden line the inbox shows beside the subject. One is normal; paragraphs of hidden text are not.
How to use this tool
1
Copy the raw message
In Gmail open the message and choose Show original; in Outlook use View source. Or copy just the HTML out of your email platform.
2
Paste and check
Paste it into the box and click Check message. Nothing is stored, logged or shared.
3
Work down the findings
Findings are ranked by severity, and each one expands to explain the problem and the fix.
4
Check the sending domain
Content is half of placement. Run an Email Health Check for SPF, DKIM, DMARC and blocklists.
Related tools
4 tools
Email Header Analyzer
Parse and analyze email headers, including SPF, DKIM and DMARC authentication results and routing information
Email Health Checker
Comprehensive email deliverability check including SPF, DKIM, DMARC, and MX records
IP Blacklist Checker
Check if IP address is blacklisted across multiple DNSBL and spam databases
DMARC Lookup
Check DMARC policy records for email authentication, reporting, and policy enforcement
Frequently asked questions
5 Q&A
Because modern filters barely weigh them. Gmail, Outlook and Yahoo decide placement mostly on sender reputation, authentication and how recipients engage. A word list would give you a number with nothing behind it, so this tool only reports things it can measure and you can fix.
No. A clean message removes the content signals, but placement also depends on SPF, DKIM and DMARC for the sending domain, the reputation of the sending IP, and recipient engagement — none of which is visible in the message itself. Use the Email Health Check and Blacklist Checker for those.
The full message if you can. Header checks — unsubscribe headers, Message-ID, Date, Reply-To and Return-Path alignment, and whether there is a plain-text part — only run when headers are present. An HTML-only paste still gets the link, image, hidden-text and structure checks.
No. The message is parsed in memory on the server and discarded when the result is returned. It is not logged, cached or saved, and this tool has no share links for the same reason.