In the Email Template Block Editor's Hyperlink Manager there is a field called Target. This refers to how the link will open when someone clicks on it. Here is what each choice means:
None: Does what the email client's or browser's default action is.
Same Window: Opens in the current window.
New Window: Opens in a new window.
Parent Window: If there are frames in the page, it would open in the frame the link is in.
Browser Window: Opens in the same window.
Search Pane: Opens in a search pane. [Internet Explorer Only]
Media Pane: Opens in the media bar. [Internet Explorer Only]
|Feature Added: Original|
|Feature Updated: 8.1.0|
|ClickDimensions Version Need: Any|