There are many wise experienced folks on this site so please help me sort out a dilemma that I am going through with one group.

I know that in a face-to-face meeting a vote on an issue or motion can be 'yay', 'nay' or 'abstain' according to general rules of order such as Roberts.
What happens when the vote is via email and only 11 of 20 respond? Does each of the non-respondents get classified as an abstention or a nay vote?
How many non-respondents totally nullifies the vote?

This must be happening in the real world with our technology.