When the ordered goods leave the company premises, the authority issues 'Confirmation of Dispatch' to the customer,stating the exact date,time,mode of dispatch and probable time it will take to reach customer's hands.

more probable

most probable

probable is an adjective

In my opinion, a positive attitude. Most customers who contact customer support are either experiencing a problem or have a question and it is highly probable that they are not in the greatest of moods. From my personal experience, a customer who hears that you are able to resolve the issue at hand and will do so with a positive attitude will usually be more cooperative and less demanding.

seem probable