What are they going to do about it?

The Mises Institute just signed me up for an email list.  The "Welcome" message contains the following predictable-yet-bizarre statement:

 Your membership is strictly voluntary, and you may leave at any time.

I wonder what Mises Instituters would propose to do about "involuntary" email subscriptions.  Prior restraint?  Jail?  Self-authorized, self-determined retribution?  An involuntary email subscription for an involuntary email subscription?  Nothing?