Phish Flagger by PhishFlagger Inc. is an email security solution designed to prevent phishing attacks and fraudulent emails. Phish Flagger inserts a sequential number, called the Phish Counter, in the subject line of outgoing emails. This patented, human-compatible technology allows recipients to verify the authenticity of incoming emails by checking if the Phish Counter matches the expected sequence. Phish Flagger aims to protect recipients from phishing attacks by flagging or quarantining suspicious emails that are out of sequence.