Displaying very long texts in a text box or a table cell will not cause QlikView to display a vertical scroll bar, unfortunately. However, it the text string doesn't fit in the available space, QlikView will try to display all text in a tooltip-like temporary window if you hover your mouse pointer over the cell. Of course, this technique also has its limitations.
Why do you want to move your email messages to QlikView?
Well, Qlikview is a BI tool, not an email program or a text editor. You can try using a text box that will display the contents of the field with lost of text. Let the user select a email and use the text box to show the details of the selected email. The text box can have scroll bars if you like.