A DC9 ACR FLC COMPLAINS THAT THEY DID NOT RECEIVE AN ACARS MESSAGE WARNING ABOUT WIND SHEAR UNTIL AFTER TKOF. THE MESSAGE WAS SENT 3 MINS PRIOR TO TKOF; BUT NOT RECEIVED UNTIL 15 MINS AFTERWARDS BECAUSE OF A SOFTWARE PROGRAM THAT BLOCKS CERTAIN MESSAGES BTWN THE TIME THAT THE ACFT LEAVES THE GATE UNTIL IT IS SAFELY AIRBORNE.

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I WAS THE CAPT ON A SCHEDULED PAX FLT FROM MEM TO SAT WITH 112 PAX; A WORKING CREW OF 5 WITH 1 COCKPIT OBSERVER ON BOARD. WE DEPARTED THE GATE AT XA36 LCL BUT DUE TO THE LARGE AMOUNT OF COMPANY DEPS; THE FLT DID NOT BECOME AIRBORNE UNTIL XB14 LCL. CONTRIBUTING TO THE DEPS WAS A BROKEN LINE OF TSTMS APCHING THE ARPT FROM THE SW -- THROUGH W AND NW. DURING THE 38 MIN TAXI TIME; GND CTL/TWR WAS MONITORED CONTINUOUSLY. AT NO TIME WAS A WINDSHEAR ALERT OF ANY TYPE BROADCAST OVER THOSE 2 FREQS. WHEN OUR FLT WAS CLRED INTO POS AND HOLD ON RWY 18R; I REQUESTED THE WIND AND TWR RPTED 200 DEGS AT 19 KTS. I HAD THE WX RADAR ON AND OBSERVED THE TSTMS MOSTLY TO THE N; AND SE OF THE FIELD; DIMINISHING OVERHEAD AND TO THE W. TKOF WAS NORMAL FOR A HVY DC9-40 WITH NO WINDSHEAR NOTED. CLB TO THE SW ON A HDG OF 215 DEGS WAS ACCOMPLISHED IN VERY LIGHT RAIN. TKOF TIME WAS AUTOMATICALLY RECORDED ON OUR ACARS UNIT AT XB14 LCL. DURING THIS CLB THE FOLLOWING MESSAGE WAS ALSO RECEIVED AT XB29 LCL: 'MESSAGE' MEM WINDSHEAR ALERT -- MEM WINDSHEAR ALERT. THIS MESSAGE WAS RECEIVED 15 MINS AFTER TKOF. THIS AIRLINE OPS DEPT HAS CHOSEN TO BLOCK ALL ACARS MESSAGES FROM THE TIME THE ACFT LEAVES THE GATE UNTIL 15 MINS AFTER TKOF UNLESS THOSE MESSAGES ARE FROM DISPATCH; LOAD CTL; OR MAINT CTL. IN SPEAKING WITH THE CHIEF DISPATCHER AFTER THIS FLT; I WAS INFORMED MESSAGES ARE SENT DIRECTLY TO OUR ACARS UNIT BYPASSING OUR DISPATCH SECTION; AND WITHOUT THEIR IMMEDIATE KNOWLEDGE; THEREFORE BEING BLOCKED UNTIL 15 MINS AFTER TKOF. I HAVE NOTIFIED THE COMPANY AND UNION SAFETY DEPTS REGARDING THIS PROB WITH THE COMMENT THAT THIS VALUABLE WX RESOURCE NEEDS TO BE REFINED; DEFINED AND DISSEMINATED -- OR SCRAPPED.