Hi Jaya, the suggestion box is a well-established idea and has been used across many companies as it brings good results. However, the readiness of the company is very important as the feedback can be negative as well. The suggestions and ideas employees give then need to be implemented, of course not all of them but the choicest few which the Senior Management thinks can be used.
Place suggestion boxes at places where all employees have access, maybe one or two on each floor, or as per the design of your floor(s).
Then send an email to all the employees about this new initiative and how the company is looking forward to some brilliant ideas from their employees and also inform them about the placement of such boxes.
I would suggest starting with asking people not to write their names, unless you are very sure that all the seniors will take the feedback and suggestions with a positive nod. Then go ahead...
All the best.
Regards,
Archna