Images can be very complicated in emails. Luckily Bootstrap email makes it easy.
Note: All images must have a height and width property on the image to size it correctly in Outlook.
To keep an element full width of it’s container, give it the img-fluid class and make sure apply the width and height properties as always to make sure it fits in Outlook.
<img class="img-fluid" width="600" height="250" src="https://bootstrapemail.com/some/image.png" alt="Some Image" />