config setting for FM 'SO_OBJECT_SEND'

Hi  Friends

Am using FM  CALL FUNCTION 'SO_OBJECT_SEND'   to  send mail to sap inbox

In one system its sending but in anther system  it is not sending  though the  sy-subrc is 0 .

Is there any  prerequisite  or  config settings need to compare in both the system which might be missing

any idea ?

EG    ABC   system one  here mail going

         XYZ    system  two   in this mail not going  .

any idea pls share