While HTML e-mail continues to evolve and become more popular, there continue to be reasons to provide a choice between HTML and plain text format. Many e-mail clients can be configured to receive text only, and the proliferation of e-mail-capable portable devices and web-based e-mail services are important to consider. Allowing the user to choose between formats ensures that they will receive content in the format they can use.
Many e-mail newsletter packages that use HTML also include uniquely identifying codes that can be tracked by the sender. If HTML e-mail is used, these privacy concerns must be addressed.