To remove the border showing around an image, right click on the image to display a list of options. Click on Image Properties.
Now that the Image Properties window has loaded, look for the attribute called Border. Enter the value of 0 in the box and click on the OK button to save the changes.
We put in the padding at least in part to make it easy for you when you're building the copy to differentiate the beginning and end of a specific piece of the message. It's also because it makes it clearer to the customer and allows you to isolate images built with hyperlinks in them. It doesn't, however, mean you have to do it that way.
By default, the system will add borders around images in your email newsletter when you create a hyperlink that is associated with the image. You can save time by setting the border to 0 before inserting the image to avoid having to edit the image properties after a hyperlink is set up.