SYSBOXBlacklist checker
Check a mail server IP against public blacklists
Enter the sending mail server's (MTA) IP address or host name above, or open /blacklist-checker/mail.example.com directly.
Best-effort checks against free public DNSBL mirrors — results can lag reality, and a busy shared IP may get rate-limited by some providers. "Greylisted" means a policy / dynamic-range list (like a residential ISP range), which isn't necessarily abuse. Use each list's own lookup/delist link to confirm and request removal.