How can I stop automatic sending of digital touch messages?

Greetings,

I finally updated to IOS 10 and am trying to get used to all the new features.

FIrst thing I tested were the new features in IMessage. I checked the digital touch messages and thought I could preview them before sending, but alas they send themselves automatically, so I accidentally sent about 10 messages before finally realizing that I was in fact sending messages....

Is there any way to stop the automatic sending of those messages and if so, how? I'd just like to preview them first, especially the scribbles.

Thanks for your help.