How to send your test
Send it from the system you want to test. If your campaigns go out through an email platform, use its test send or a one-person list. If you send from a mailbox, send from that mailbox.
A test sent from webmail tests webmail, not your campaign tool: the sending server, the signature and most of the headers come from whatever actually sends the message. Use the same From address, template and links you send for real. Each address takes one email; get a new one for the next test.
What happens to your email
Our server reads it once, as it arrives, to build the report. Only the report is kept: the body is never stored. The report holds the message’s header fields, its links and the first line of its text, so you can read them back, and it is deleted after 7 days. Anyone with its link can read it, so share the link only with people you want to see it. The privacy policy has the details.
What it checks
A score out of 10, and the sender rules
One number for the whole message, with the points each problem costs, and the requirements Gmail, Yahoo and Microsoft publish for senders, rule by rule.
Authentication
SPF, DKIM and DMARC, worked out by us from the message and live DNS (every DKIM signature verified, SPF evaluated against the IP that delivered it), whether each lines up with your From domain, and BIMI.
The sending server
The IP address that delivered the message, its reverse DNS, the name the server gave when it connected, and whether your bounce and reply domains can receive mail.
Reputation
The sending IP against the 25 public blacklists that answer open queries. The ones that need a paid key are listed as not checked, never as clean.
The delivery route
Every server the message passed through, oldest first, with the protocol each hop used, whether it was encrypted and how long it waited.
Content
The plain-text version, Gmail clipping, links and URL shorteners, tracking pixels, images and alt text, the preview line inboxes show, HTML that mail apps strip, SpamAssassin's content rules, attachments and one-click unsubscribe.
Headers
From, Message-ID, Date, recipients and the fields that must appear once, fake "Re:" replies, and what the headers reveal about the sending software. Every field is listed as it arrived, with what the receiving relay recorded shown beside our results as a cross-check.