mailto is a

Uniform Resource Identifier A Uniform Resource Identifier (URI), formerly Universal Resource Identifier, is a unique sequence of characters that identifies an abstract or physical resource, such as resources on a webpage, mail address, phone number, books, real-world obje ...

(URI) scheme for email addresses. It is used to produce

hyperlink In computing, a hyperlink, or simply a link, is a digital reference providing direct access to Data (computing), data by a user (computing), user's point and click, clicking or touchscreen, tapping. A hyperlink points to a whole document or to ...

s on

websites A website (also written as a web site) is any web page whose content is identified by a common domain name and is published on at least one web server. Websites are typically dedicated to a particular topic or purpose, such as news, education ...

that allow users to send an

email Electronic mail (usually shortened to email; alternatively hyphenated e-mail) is a method of transmitting and receiving Digital media, digital messages using electronics, electronic devices over a computer network. It was conceived in the ...

to a specific addresses directly from an

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

document, without having to copy it and entering it into an

email client An email client, email reader or, more formally, message user agent (MUA) or mail user agent is a computer program used to access and manage a user's email. A web application which provides message management, composition, and reception functio ...

. It was originally defined by

Request for Comments A Request for Comments (RFC) is a publication in a series from the principal technical development and standards-setting bodies for the Internet, most prominently the Internet Engineering Task Force (IETF). An RFC is authored by individuals or ...

(RFC) 1738 in December 1994, expanded by RFC 2368 in July 1998, and refined by RFC 6068 in October 2010.

Examples

"mailto" can be used within an

document to generate a link for sending email: Send email Clicking on the hyperlink automatically opens the default email client, with the destination email address pre-filled. It is possible to specify initial values for headers (e.g. subject, cc, etc.) and message body in the URL. Blanks, carriage returns, and linefeeds cannot be directly embedded but must be

percent-encoded URL encoding, officially known as percent-encoding, is a method to encode arbitrary data in a uniform resource identifier (URI) using only the US-ASCII characters legal within a URI. Although it is known as ''URL encoding'', it is also used more g ...

: Send email Multiple addresses can be specified: Send email The address can be omitted: Share this knowledge...Only the initial header must use a question mark (?) prepended. All subsequent headers require an ampersand (&). Should this not be the case, the scheme will not properly copy over the headers to the email client.

Security and privacy

A number of security issues are mentioned i
RFC 6068
one of them being robotic address harvesting. Mailto constructs are locatable within HTML pages by automated means which typically include the use of DOM constructs or

regular expression A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...

s. Addresses harvested by such means are liable to be added to

spam Spam most often refers to: * Spam (food), a consumer brand product of canned processed pork of the Hormel Foods Corporation * Spamming, unsolicited or undesired electronic messages ** Email spam, unsolicited, undesired, or illegal email messages ...

mers' mass-mailing lists and thus to receive large amounts of unwanted mail. While methods exist to "harden" mailto links against harvesting—

address munging Address munging is the practice of disguising an e-mail address to prevent it from being automatically collected by unsolicited bulk e-mail providers. Address munging is intended to disguise an e-mail address in a way that prevents computer soft ...

and

JavaScript JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior. Web browsers have ...

-based address

obfuscation Obfuscation is the obscuring of the intended meaning of communication by making the message difficult to understand, usually with confusing and ambiguous language. The obfuscation might be either unintentional or intentional (although intent ...

among them—these protections can be circumvented by sufficiently sophisticated harvesting robots. Other techniques, like walling the address behind a

CAPTCHA Completely Automated Public Turing Test to tell Computers and Humans Apart (CAPTCHA) ( ) is a type of challenge–response authentication, challenge–response turing test used in computing to determine whether the user is human in order to de ...

or similar "humanity check", provide security on par with that available for other contact methods, most notably

web forms ASP.NET is a server-side scripting, server-side web-application framework designed for web development to produce dynamic web pages. It was developed by Microsoft to allow programmers to build dynamic web sites, web application, applications a ...

, which experience similar challenges with preventing spam.

References

{{URI scheme Email URI schemes Web 1.0