Rich emails

To add a hyperlink, from the template editor, go to advanced options, click on "insert link" and set up your link.
image show how to select the insert link setup in the menu
Select the menu "insert link"
setting your http link in mail merge for gmail
Then set your link
You can set the URL, the text displayed, the text displayed when the reader hovers the text (Title), and the behavior of the click ( open a new tab, or open in the current windows).