The priority is used to order the queue. Higher numbers mean lower priorities. The priority increases as the message sits in the queue. The initial priority depends on the message class and the size of the message. Used exclusively for Delivery Status Notifications.
R Contains a recipient address.
There is one line for each recipient. S Contains the sender address. There is only one of these lines. T Contains the message creation time used to compute when to time out the message. V Specifies the version number of the queue file format used to allow new sendmail binaries to read queue files created by older versions.