The mailq command prints the list of messages that are in the mail queue. The mail queue is where outgoing mail is stored until a receiving server connection is available. The mailq command is the same as the sendmail -bp command, which also prints the mail queue.The mailq command is part of the topic 108.3: Mail transfer agent (MTA) basics, which is one of the objectives of the LPI Linux Administrator - 102 exam12.Reference:1: https://learning.lpi.org/en/learning-materials/102-500/2: https://www.lpi.org/our-certifications/exam-102-objectives/