The
Precedence: header, when the
QueueSortOrder option (QueueSortOrder) is appropriately set, is used internally by
sendmail to order the processing of messages in
its queue. A full description of the possible field values for this
header is given in Section 25.10.1. The effect of those
values on ordering the queue is described in Section 11.7.
The Precedence: header should never be declared as
an H line in the configuration file. However,
P precedence lines should be declared in that
file.
