Run your draft through SpamAssassin before you send it
Paste the headers and body of an email, or upload an .eml file: the score and triggered rules show up in plain language, with what to fix. Nothing is sent, nothing is kept.
How it works
- Paste your draft — the headers (From, Subject, Date…) and the message body, exactly as your software would send them. You can also upload an .eml file directly.
- Run the analysis — the message is passed through SpamAssassin locally, with no network request at all: nothing is sent, not to us, not to a third party, not to the recipient.
- Read the score — every triggered rule shows up with its weight, a plain-language explanation and advice to fix it.
- Fix it and try again — adjust your draft, paste it back in, and check the score drops before sending it for real.
Use cases
- Before an important send — a job application, a sales follow-up or a newsletter: spot the formatting mistakes that tip a legitimate message into spam.
- Debugging an automated send — a script or an application that sends emails often forgets a mandatory header (Message-Id, Date, To); this tool spots it right away.
- Understanding an email already flagged as spam — paste a copy of it to see which rules it triggered, and avoid repeating the same mistakes.
- Training a team — show concretely why certain wording, layout or headers penalize a message.
What the tool doesn’t do / limits
- The analysis runs in local mode only: no blacklist (DNSBL) lookups, no check of your IP or domain reputation. The score you get here is therefore not the one a real destination server would see. For a check that accounts for your actual sending reputation, head to the deliverability test, where you send a real test message from your own mailbox to read the full chain (authentication, IP, blacklists) — or, for a message already sent, use the header analyzer to check SPF, DKIM and DMARC.
- Nothing is sent or kept: the message stays in memory for the duration of the request and disappears afterwards, like MailSync's other instant tools.
- The analysis limit is 512 KB per message: beyond that, the content is truncated and the tool says so instead of guessing.
- The dictionary of explained rules covers the most frequent cases; a rule missing from the dictionary shows its original description, in English, as provided by SpamAssassin itself.
Frequently asked questions
What exactly does this tool analyze? +
The message you paste or upload is passed through SpamAssassin locally, on this server: no network request, nothing is sent to a third party or to a recipient. You get the score, the triggered rules and an explanation for each one.
My score here differs from what the recipient will see, why? +
This analysis runs in local mode (SpamAssassin's -L option): it ignores blacklists (DNSBL) and your IP or domain reputation, which a real destination server does check. That's the role of the deliverability test, which really sends a test message — otherwise, for a message already sent, the header analyzer checks SPF, DKIM and DMARC.
Are all triggered rules explained? +
The most frequent rules have a plain-language explanation and advice to fix them. A rarer rule shows its original description, in English, as provided by SpamAssassin.
What happens to my data? +
Nothing is kept. The submitted message stays in memory for the duration of the request and disappears afterwards, never touching disk or a database.
How much does it cost? +
Free, with no limit on the number of analyses beyond the anti-abuse rate (5 analyses per 15 minutes, the same for everyone).