6.2.6 QMGR_JOB：针对特定邮件和MDA的发送任务

struct QMGR_JOB {   QMGR_MESSAGE *message;          /*message delivered by this job */   QMGR_TRANSPORT *transport;              /*transport this job belongs to */   QMGR_JOB_LIST message_peers; /* permessage neighbor linkage */   QMGR_JOB_LIST transport_peers;         /*per transport neighbor linkage */   QMGR_JOB_LIST time_peers;                  /*by time neighbor linkage */   QMGR_JOB *stack_parent;             /*stack parent */   QMGR_JOB_LIST stack_children;   /*all stack children */   QMGR_JOB_LIST stack_siblings;    /*stack children linkage */   int     stack_level;                 /* job stack nesting level (-1means                                                * it's not on the lists at all) */   int     blocker_tag;                /* tagged if blocks the job list*/  struct HTABLE *peer_byname;/* message job peers, indexed by * domain */                                                * domain */   QMGR_PEER_LIST peer_list;            /*list of message job peers */   int     slots_used;                           /* slots used duringpreemption */   int     slots_available;          /* slots available for preemption (in                                                * multiples of slot_cost) */   int     selected_entries;                /* # of entries selected fordelivery                                                * so far */   int     read_entries;              /* # of entries read in-core sofar */   int     rcpt_count;                           /* used recipientslots */   int     rcpt_limit;                    /* available recipient slots*/};

read_entries:已建立的QMGR_ENGRY。每执行一遍qmgr_entry_create函数，read_entries递增1。