By default in our organisation no one can able to receive outside mails except few like HR and other sales team to their inbox. All the employees have certain restriction to send/receive emails from outside organisation (internet). Few of the users who is in sepecific department they want to recevice mails from there vendors and others.
Create a distribution group and add those users in to this group.
Go to Exchange management console—>Recipient configuration—>Distribution group—>Mail flow settings—>Message delivery restrictions—>properties—> clear the checkbox “require that all the senders are authenticated”
Now these users are able to receive emails from outside organisation.