HTML Email

HTML email is the use of a subset of HTML (often ill-defined) to provide formatting and semantic markup capabilities in email that are not available with plain text.

Most graphical email clients support HTML email, and many default to it. Many of these clients include both a GUI editor for composing HTML emails and a rendering engine for displaying received HTML emails.

HTML mail allows the sender to properly express quotations (as in inline replying), headings, bulleted lists, emphasized text, subscripts and superscripts, and other visual and typographic cues to improve the readability and aesthetics of the message, as well as semantic information encoded within the message, such as the original author and Message-ID of a quote. Long URLs can be linked to without being broken into multiple pieces, and text is wrapped to fit the width of the user agent's viewport, instead of uniformly breaking each line at 78 characters (defined in RFC 5322, which was necessary on older text terminals). It allows in-line inclusion of tables, as well as diagrams or mathematical formulae as images, which are otherwise difficult to convey (typically using ASCII art).