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mailto is a Uniform Resource Identifier (URI) scheme for email addresses. It is used to produce hyperlinks on websites that allow users to send an email to a specific address without first having to copy it and and enter it into an email client. It was originally defined in Request for Comments (RFC) 2368, published in July 1998,[1] and refined in RFC 6068, published in October 2010.[2]


Using "mailto" within a HTML document to generate a link for sending email:

<a href="">Send email</a>

It is also 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 embedded but must be percent-encoded.

<a href="">Send email</a>

Multiple addresses can also be specified:[2]

<a href=",">Send email</a>

The address can also be omitted:

<a href="mailto:?to=&subject=mailto%20with%20examples&body=">Share this knowledge...</a>

Security and privacy[edit]

See also: Address munging

A number of security issues are mentioned in RFC2368, however the greatest concern is that of robotic address harvesting. Mailto constructs are locatable within HTML pages by automated means which typically include the use of DOM constructs or regular expressions. Addresses harvested by such means are liable to be added to spammers' mass-mailing lists and thus to receive large amounts of unwanted mail.

While methods exist to "harden" mailto links against harvesting—address munging and JavaScript-based address obfuscation among them—these protections can be circumvented by sufficiently sophisticated harvesting robots. Other techniques, like walling the address behind a CAPTCHA or similar "humanity check", provide security on par with that available for other contact methods, most notably web forms, which experience similar challenges with preventing spam.


  1. ^ Hoffman, Paul; Masinter, Larry; Zawinski, Jamie (July 1998). "The mailto URL scheme". Retrieved 26 September 2015. 
  2. ^ a b Duerst, Martin; Masinter, Larry; Zawinski, Jamie (October 2010). "The 'mailto' URI Scheme". Retrieved 26 September 2015.