: Hackers use automated tools to "check" the credentials against mail servers (SMTP/IMAP). If the login works, it is added to a "valid base" file, which is much more valuable than raw, unverified data.
Exposure in such a database can lead to severe personal and professional consequences: 530k Mail Access valid base.txt
Credential Stuffing Prevention: Guide for Users & Businesses : Hackers use automated tools to "check" the