What does the HTML email attachment format do?

The HTML email attachment format is designed to embed content directly within the email body, which allows for richer formatting and more visually appealing presentation of the message. This includes the use of images, colors, hyperlinks, and other multimedia elements that enhance the overall communication experience for the recipient. By embedding the content, users can view the message exactly as intended without needing to download any attachments, leading to a more seamless interaction with the email.

The other options do not accurately describe the functionality of HTML emails. While security and file size considerations are important aspects of email communication, they do not pertain specifically to the capabilities of the HTML format in embedding content within the email itself.