How to Send mail from Oracle APEX

https://www.youtube.com/watch?v=YhT_Hmdkjvk

Second :  Enabling Network Service 
 

DECLARE
  ACL_PATH VARCHAR2(4000);
BEGIN
    -- Look for the ACL currently assigned to '*' and give APEX_190100
    -- the "connect" privilege if APEX_190100
    -- does not have the privilege yet.
  SELECT ACL INTO ACL_PATH FROM DBA_NETWORK_ACLS
    WHERE HOST = '*' AND LOWER_PORT IS NULL AND UPPER_PORT IS NULL;
  IF DBMS_NETWORK_ACL_ADMIN.CHECK_PRIVILEGE (ACL_PATH,'APEX_190100','connect') IS NULL THEN
    DBMS_NETWORK_ACL_ADMIN.ADD_PRIVILEGE(ACL_PATH,'APEX_190100', TRUE, 'connect');
  END IF;
  EXCEPTION
    -- When no ACL has been assigned to '*'.
  WHEN NO_DATA_FOUND THEN
    DBMS_NETWORK_ACL_ADMIN.CREATE_ACL('power_users.xml',
    'ACL that lets power users to connect to everywhere',
    'APEX_190100', TRUE, 'connect');
  DBMS_NETWORK_ACL_ADMIN.ASSIGN_ACL('power_users.xml','*');
END;
/
COMMIT;

BEGIN

  DBMS_NETWORK_ACL_ADMIN.add_privilege (
    acl          => 'power_users.xml',
    principal    => 'STOCK',
    is_grant     => TRUE,
    privilege    => 'connect');
  COMMIT;
END;
/