Few Emails are going to Junk folders in outlook

Hello Team

Iam using the script to send the emails automatically from exchnage 2010 mailbox. in that Few of the emails are automattically to going to Junk folders

How do i stop by going to junk folder

This script is automatically pick the user from the EMC mailbox and send randomly from the powershell script

is there anything  need to change in HUB server

ramakrishnan