smtp-check - SMTP setup checker
smtp-check [-port port] [-localname domain] [-skip_tls_check] domain
smtp-check is a command-line too for checking SMTP setups (DNS records, TLS certificates, SPF, etc.).
-port port:
Port to use for connecting to the MX servers.
-localname domain:
Local name to use for the EHLO command.
-skip_tls_check:
Skip TLS check (useful if connections are blocked).