Non admin windows users cannot email remittances from Myob Exo

Users are using rdp to access terminal server and use exo, which is located on another server.

If the user is an admin user on the TS, they can email creditor remittances. If they are not an admin user, they are not able to email.

Previously this issue was fixed for them with a script to amend permissions and policies but we do not have access to the script.

Email is set up with smtp on exo config. 

Has anyone else encountered this and would you be able to advise what settings and permissions need to be configured to allow non admin users to have the necessary privileges and permissions to email, so that Exo will see this.