With so many image file formats available, BMP, EPS, JPEG, PNG, and GIF ...
Question: How do you determine which is right for your email?
Each format produces variances in file size, compression, and quality. To make things more confusing, support for specific file types can also vary between email clients. I will weigh the pros and cons of the JPEG file format.

JPEG images (short for Joint Photographic Experts Group) are full-color images that dedicate at least 24 bits of memory to each pixel, resulting in images that can incorporate 16.8 million colors, and are frequently referenced by their file extension, JPG. JPEGs are also lossy, meaning they retain all color information, but compress file size by selectively discarding data, and that compression can result in a loss of quality. In most design programs, you can choose the degree of compression you wish to apply to individual images, just be aware that by doing so, you also will alter the quality of the image. As a result, if you choose the maximum quality option, your image will most likely be indistinguishable from your original photograph, albeit with a correspondingly larger file size