HTML email: Difference between revisions

Revision as of 16:53, 13 March 2020

Revision as of 04:33, 14 September 2020

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{{Use dmy dates|date=January 2013}}

'''HTML email''' is the use of a [[subset]] of [[HTML]] to provide formatting and [[semantic web|semantic]] markup capabilities in [[email]] that are not available with [[plain text]]:<ref name=":0">{{Cite web|title = Text Email vs HTML Email – The Pros and Cons {{!}} Thunder Mailer – Mass Emailing Software|url = http://www.thundermailer.com/text-email-vs-html-email-the-pros-and-cons/|website = www.thundermailer.com|access-date = 2016-01-30}}</ref> Text can be linked without displaying a [[URL]], or breaking long URLs into multiple pieces. Text is wrapped to fit the width of the viewing window, rather than uniformly breaking each line at 78 characters (defined in RFC 5322, which was necessary on older [[Data terminal#Text terminals|text terminals]]). It allows in-line inclusion of images, [[Table (information)|table]]s, as well as diagrams or [[mathematical formula]]e as images, which are otherwise difficult to convey (typically using [[ASCII art]]).

== Adoption ==

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Although the difference in download time between plain text and mixed message mail (which can be a factor of ten or more) was of concern in the 1990s (when most users were accessing email servers through slow [[modem]]s), on a modern connection the difference is negligible for most people, especially when compared to images, music files, or other common attachments.<ref>[http://www.georgedillon.com/web/html_email_is_evil_still.shtml HTML Email — Still Evil?]</ref>

== JoinMember4d ==

== Security vulnerabilities ==

HTML allows a link to be displayed as arbitrary text, so that rather than displaying the full URL, a link may show only part of it or simply a user-friendly target name. This can be used in [[phishing]] attacks, in which users are fooled into believing that a link points to the website of an authoritative source (such as a bank), visiting it, and unintentionally revealing personal details (like bank account numbers) to a scammer.

If an email contains [[web bug]]sbugs (inline content from an external server, such as a [[Digital image|picture]]), the server can alert a third party that the email has been opened. This is a potential [[email privacy|privacy]] risk, revealing that an email address is real (so that it can be targeted in the future) and revealing when the message was read. For this reason, all modern popular email clients (as of year-2019) do not load external images until requested to by the user.

HTML content requires email programs to use engines to parse, render and display the document. This can lead to more security vulnerabilities, denial of service or low performance on older computers.

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The multipart type is intended to show the same content in different ways, but this is sometimes abused; some [[email spam]] takes advantage of the format to trick [[spam filter]]s into believing that the message is legitimate. They do this by including innocuous content in the text part of the message and putting the spam in the HTML part (that which is displayed to the user).

Most email spam is sent in HTML{{CitationHTMLsgptogel888@gmail

Com<ref needed|datename=December":0" 2013}}/> for these reasons, so spam filters sometimes give higher spam scores to HTML messages.{{Citation needed|date=December 2013}}

In 2018 [[EFAIL]] was unveiled, a severe vulnerability which could disclose the actual content of encrypted HTML emails to an attacker.