What we check
- A real message, not just a DNS form
- SPF / DKIM / DMARC for the From domain
- DNSBL and PTR of the sending IP
- Subject/body: spam words, CAPS, short URLs
- A–F grade with copy-paste fixes
How to use
- Copy the test address on the page
- Send a message to it from your server or mailbox
- Wait 10–60 seconds — keep the tab open
- Read findings and fix DNS/content
Deliverability tips
Filters look at both infrastructure and wording. Fix auth and content together.
Practice
- Sign DKIM with the same domain as From
- Never use +all in SPF
- SMTP PTR should match EHLO
- Avoid public URL shorteners
- Include a text part, not only an image
When you need it
- Before a bulk campaign
- After changing ESP or your Postfix/Exim
- When Gmail/Mail.ru file mail as spam
- Checking sending-IP reputation
FAQ
Where do I send mail?
To the unique …@inbox.supermail.dmosk.net address shown on the page.
How long does the inbox live?
About 30 minutes. Create a new address when it expires.
Do you read other people’s mail?
Only what you send to the test address. Bodies are not kept past the session.
Is this a mail-tester clone?
Same flow: inbox → message → report. The checks and wording are ours.
Is it free?
Yes.
How is the grade calculated?
We start at 100 and subtract for critical/high/medium/low findings.