Greylisting: whitelist doesn't work

I'm trying to create the whitelist according to the procedure in Apple manual but without any success.

The procedure is described here:

https://help.apple.com/advancedserveradmin/mac/10.7/#apd5178A1BB-15A5-46B5-ACFD- 2C0550626FB2

I made a list of Gmail servers, so the output of "serveradmin settings mail:postfix:host_whitelist" is following:

mail:postfix:host_whitelist:_array_index:0 = "mail-pz0-f50.google.com"

.........

mail:postfix:host_whitelist:_array_index:3 = "na3sys010aog110.obsmtp.com"

mail:postfix:host_whitelist:_array_index:4 = "na3sys010aog112.obsmtp.com"

mail:postfix:host_whitelist:_array_index:5 = "na3sys010aog108.obsmtp.com"

mail:postfix:host_whitelist:_array_index:6 = "na3sys010aog105.obsmtp.com"

mail:postfix:host_whitelist:_array_index:7 = "na3sys010aog102.obsmtp.com"

mail:postfix:host_whitelist:_array_index:8 = "na3sys010aog113.obsmtp.com"

mail:postfix:host_whitelist:_array_index:9 = "na3sys010aog114.obsmtp.com"

mail:postfix:host_whitelist:_array_index:10 = "na3sys010aog101.obsmtp.com"

mail:postfix:host_whitelist:_array_index:11 = "na3sys010aog103.obsmtp.com"

mail:postfix:host_whitelist:_array_index:12 = "na3sys010aog107.obsmtp.com"

mail:postfix:host_whitelist:_array_index:13 = "na3sys010aog111.obsmtp.com"

mail:postfix:host_whitelist:_array_index:14 = "mail-pb0-f49.google.com"

mail:postfix:host_whitelist:_array_index:15 = "exprod6og101.obsmtp.com"

mail:postfix:host_whitelist:_array_index:16 = "exprod6og104.obsmtp.com"

mail:postfix:host_whitelist:_array_index:17 = "exprod6og102.obsmtp.com"

mail:postfix:host_whitelist:_array_index:18 = "mail-yx0-f177.google.com"

But, these servers are still being Greylisted.

What I'm doing wrong?

Thank you in advance!