What type of software can greatly lessen the volume of unsolicited commercial emails received by users?

Anti-spam software is specifically designed to identify and filter out unsolicited commercial emails, commonly known as spam. This type of software employs various techniques such as heuristics, machine learning, and predefined filters to detect characteristics typical of spam emails, which helps reduce their presence in the user's inbox.

By analyzing patterns and using blacklists of known spammers, anti-spam software can effectively segregate these unsolicited messages from legitimate correspondence. This results in a cleaner inbox for users and minimizes the distractions and potential security risks associated with spam emails. Conversely, firewall software primarily focuses on network security and preventing unauthorized access, while anti-virus software centers on detecting and removing malware. Backup software, on the other hand, is intended for data safeguarding and recovery, and does not deal with email filtering. Thus, anti-spam software is the most appropriate choice for reducing unwanted commercial emails.