When you paste an image into an e-mail or a Word document, by default it has no borders. This may be OK for what you want, but it can make it very hard to distinguish what is an image and what is a clickable link:
An image in Outlook with no border
In the example above, the blue text is part of the image, and you can't click on the links.
To make it a bit easier for your recipients to tell the difference, it's a good idea to put a border around the image. Outlook makes this very easy when you right-click on the image:
Displaying the Style option from right-clicking on the image
When you click on Style, you get a palette of different border options that you can apply with a single click. I prefer the first one on the list:
The Border options in Styles
The result is a nice shadowed border that makes it much more obvious that the information is part of an image, and that nothing inside of the border is clickable (plus, it just gives it a polished look):
An image in Outlook with a styled border
This also works with images in other Office software, such as Word.