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 e-mail clients support HTML email, and many default to it.[1] Many of these clients include both a GUI editor for composing HTML e-mails and a rendering engine for displaying received HTML e-mails.
Controversy
Use of HTML in e-mail is controversial:
Benefits
- The sender can express complex formatting, such as subscripts and superscripts, in scientific or mathematical formulas. Note that Unicode supports many such complex characters; however, font support issues with Unicode limit the usefulness of this possibility.
- The sender can properly express headings, bulleted lists, emphasize text, or use other visual cues to improve the readability and aesthetics of the message.
- Allows in-line inclusion of diagrams or mathematical formula as images, which are otherwise difficult to convey (typically using ASCII art).
Drawbacks
- A few recipients have e-mail clients that cannot display HTML. This may be mitigated by the inclusion of an automatically generated plain text version, which may be missing important formatting information (e.g. an equation may lose a superscript and take on an entirely new meaning).
- HTML e-mail is larger than plain text. Even if no special formatting is used, there will be the overhead from all the tags needed in a minimal HTML document, and if formatting is heavily used it may be much higher (e.g. a single fully specified font tag is at least equivalent to a full sentence of text). Many email clients are configured to send a plain text version of a message along with the HTML version, further increasing the size.
- Some senders may excessively rely upon large, colorful, or distracting fonts making all but the shortest messages more difficult to read.
- HTML allows for a link to have a different target than the link's text. This can be a security issue for users, who may be fooled into believing that a link points to the website of an authoritative source (such as a bank) and unintentionally revealing personal details to a scammer.
- The viewing of embedded external content, such as an image in an email, can alert a third party that the e-mail has been opened. This is a potential privacy risk, and the reason for which some e-mail clients do not load external images by default.
- Most E-mail spam is sent in HTML so spam filters (such as Spamassassin) give high spam scores to HTML messages.
- Many HTML-based GUI email clients automatically convert common plain text characters, e.g. — and ", into non-plain text equivalents. This can cause translation problems in other users' clients.
For these reasons many mailing lists deliberately block HTML e-mail, either stripping out the HTML part to just leave the plain text part or rejecting the entire message.
References
- ^ Configuring Mail Clients to Send Plain ASCII Text — E-mail client programs
External links
- Dan's Mail Format Site
- Configuring Mail Clients to Send Plain ASCII Text — Argues that HTML (and MIME in general) should never be used in mail
- HTML Email - Still Evil?
- HTML e-mail is STILL evil!!!
- HTML Email Isn't Rich
- The Dying Art of Plain Text Email