The NoSolicitado blacklist is a real-time blacklist primarily focused on unsolicited email sent to domains in Latin America, particularly Argentina. While it might not be a top priority for senders focusing on other regions, it's essential to monitor blacklists in general because being listed, even on smaller ones, can negatively impact sender reputation and deliverability. Continuous listing could signal broader problems. Monitoring key blacklists, including NoSolicitado if you send to Latin America, is crucial. Addressing the root cause of any listings is important.