Links and Webs - HTML and XHTML: The Definitive Guide - page 305

You may include multiple recipients in the mailto URL, separated by
commas. For example, this URL addresses the message to all three re-
cipients:
mailto:[e-mail],[e-mail],[e-mail]
There should be no spaces before or after the commas in the URL.
6.2.5.1. Defining mail header fields
The popular browsers open an email helper or plug-in application when
the user selects a mailto URL. It may be the default email program
for their system, or a common application such as Outlook Express
with Internet Explorer or Netscape's built-in Communicator. With some
browsers, users can designate their own email programs for handling
mailto URLs by altering a specification in their browsers' Options or
Preferences.
Like http search parameters that you attach at the end of the URL, sep-
arated by question marks ( ? ), you include email-related parameters with
the mailto URL in the HTML document. Typically, additional parameters
may include the message's header fields, such as the subject, cc (car-
bon copy), and bcc (blind carbon copy) recipients. How these additional
fields are handled depends on the email program.
A few examples are in order:
mailto:[e-mail]?subject=Loved your book!
mailto:[e-mail]?cc=[e-mail]
mailto:[e-mail]?bcc=[e-mail]
As you can probably guess, the first URL sets the subject of the mes-
sage. Note that some email programs allow spaces in the parameter
value and others do not. Annoyingly, you can't replace spaces with their