A mail in survey? Yeah at least add an asterisk on it.
Why ? It's how the absentee balloting works too. And the Dispatch poll has been good most of the time.
Who is crazy enough to pay a stamp to answer a poll?
Did they at least made the reply postage paid? That might have been a good polling method in the 1800s, LOL.
If it worked in the 1800s, why shouldn't it work today ... ?
(This might actually be a cheaper method of polling, than placing 40.000 calls to people for a sample of 2.000 - who could not even be at home - but if you mail them, there's a good chance they will return the form at some point).