Francis received a spoof email asking for his bank information.

MxToolbox is a comprehensive tool designed for analyzing email headers and diagnosing various email delivery issues. When Francis received a spoofed email asking for his bank information, using MxToolbox to analyze the email headers would be appropriate. This tool helps in examining the source of the email, tracking the email's path across the internet from the sender to the receiver, and identifying any signs of email spoofing or malicious activity. It provides detailed information about the email servers encountered along the way and can help in verifying the authenticity of the email sender. Other options like EventLog Analyzer, Email Checker, and PoliteMail are tools used for different purposes such as analyzing system event logs, checking email address validity, and managing email communications, respectively, and do not specifically focus on analyzing email headers to the extent required for investigating a spoofed email incident.