SPF · DKIM · DMARC · TLS

mxtool

Will your mail arrive, and is it safe on the way? Check a domain's mail records and servers, a site's certificate and TLS, flatten an SPF record that hit the limit, or read the headers of a message that went to spam.

Mail SSL SPF Headers

MX, SPF, DKIM, DMARC, STARTTLS, blacklists

Try gmail.com proton.me ssl github.com ssl smtp.gmail.com:587 spf outlook.com

Mail checkMX and reverse DNS, SPF with its lookup count, DMARC policy and reports, DKIM keys and their size, MTA-STS, TLS-RPT, BIMI, a STARTTLS handshake with each mail server, and 13 blacklists. SSL / TLS checkWho issued the certificate and until when, whether the chain is complete, which TLS versions and ciphers are accepted, forward secrecy, OCSP stapling, HTTP/2, HSTS, CAA. Mail ports too: 465, 587, 993, 995, 25. SPF flattenerEach include costs a DNS lookup and 10 is the limit: past it, SPF fails everywhere. See the tree, then get the same record as plain addresses, split into parts if it's long. Header readerPaste the headers of a message: every server it passed, how long each hop took, and what SPF, DKIM and DMARC said. It runs in your browser; nothing is sent anywhere.

Read-only checks: this site looks up public DNS and opens a TLS connection or an SMTP conversation up to STARTTLS. It never sends mail. Nothing is stored.