Another utility to analyze state of deployment of security-related email protocols.
Needs Go toolchain.
go get github.com/foxcpp/mailsec-check mailsec-check example.org $ mailsec-check protonmail.com -- Source forgery protection [+] DKIM: _domainkey subdomain present; DNSSEC-signed; [+] SPF: present; strict; DNSSEC-signed; [+] DMARC: present; strict; DNSSEC-signed; -- TLS enforcement [+] MTA-STS: enforced; all MXs match policy; [+] DANE: present for all MXs; DNSSEC-signed; no validity check done; -- DNS consistency [+] FCrDNS: all MXs have forward-confirmed rDNS [+] DNSSEC: A/AAAA and MX records are signed; $ mailsec-check disroot.org -- Source forgery protection [+] DKIM: _domainkey subdomain present; DNSSEC-signed; [+] SPF: present; strict; DNSSEC-signed; [ ] DMARC: present; no-op; DNSSEC-signed; -- TLS enforcement [ ] MTA-STS: not enforced; all MXs match policy; [+] DANE: present for all MXs; DNSSEC-signed; no validity check done; -- DNS consistency [ ] FCrDNS: no MXs with forward-confirmed rDNS [+] DNSSEC: A/AAAA and MX records are signed;