Resist the Urge to Send Image-Only Emails
Images don't resize on all devices. A HTML email campaign with a combination of text and images is more flexible to optimize for rendering across devices.
CAN-SPAM compliance information as text
No matter how you decide to handle the balance of text and images in your email, unsubscribe copy and address information should always be in text to ensure subscribers are able to see the information when images are blocked.
It's important to remember to take into consideration your list and program. Use analytics to determine the most prominent devices being used by your recipients and to what degree changes to your creative will affect engagement. Test different templates and analyze where recipients are clicking to see how and when subscribers interact with images. In the end, you'll likely determine that while there's a time and place for images, they're not a silver bullet.