Check file security, url/domain or email security
VirusTotal
https://www.virustotal.com/gui/home/upload
Whatismyip
https://whatismyipaddress.com/blacklist-check
Barracuda
https://www.barracudacentral.org/lookups
mxtoolbox
https://mxtoolbox.com/blacklists.aspx
haveibeenpwned
https://haveibeenpwned.com/
dnschecker
https://dnschecker.org/ip-blacklist-checker.php
shodan IoT
https://www.shodan.io/
references
https://www.spamhaus.org/drop/