While visiting the website of META, Mark encounters a pop$-$up box that reads,

$$Our e$-$mail daily newsletter VRCrypt$-$Profit is available by subscription at the rate of one dollar per issue.

To subscribe, enter your e$-$mail address below and click

on $$SUBSCRIBE$.$

Mark enters his e$-$mail address and clicks on $$SUBSCRIBE$.$

Has Mark entered into an enforceable contract? Explain.