<Li> PYR, meaning Per Your Request . The recipient is informed that the sender is replying to a previous email in which she was given a task . </Li> <Li> QUE, meaning Question . The recipient is informed that the sender wants an answer to this e-mail . </Li> <Li> RB, meaning Reply By . Used with a time indicator to inform the recipient that the sender needs a reply within a certain deadline, e.g. RB + 7 meaning Reply By one week (7 days). </Li> <Li> RLB, meaning Read later . Used when sending personal or informational email to a business email address . Immediate response not required . </Li>

What is the meaning of na in mail