Closed Account Surveys

I am currently looking for different ideas on how to accomplish our Closed Account Surveys completed each month by our Supervisory Committee.  At this point, we do it through a 'mail-out' survey, providing the return envelope and a pre-typed survey that the member just needs to complete and return.  We've discussed utilizing email or text tactics, however, don't feel the response would be as great.  Are there any others utilizing any other format that seems to work well for them?