What I could find was:
Setting Firefox's mail client
- At the top of the Firefox window On
the menu bar, click on the Tools
Firefox Edit menu, and select
- Select the Applications panel.
- Search for the Content-type: mailto
and select it.
Click on the Actions column in the
mailto row, to change the action.
Always ask will prompt you each time you use a mail function for which
program or service to use.
- Use (default) will automatically launch your operating
system's e-mail program (e.g. Thunderbird, Outlook, Entourage, Evolution) to its message composition window.
- For instructions on how to change your operating system's default e-mail program, see the next section of this article.
- Use will open your webmail service's (e.g. Yahoo! Mail, Gmail, Hotmail) message composition page inside Firefox. For more information
about using webmail services, see the
Using webmail services section of
- Use other... will let
you specify an external program for
Firefox to launch.
Details... will let you view
information about or remove the
webmail services that Firefox can
Click OK to close the Options
Click Close to close the
Preferences windowClose the
Or read this:
The default mail client is the program that opens when you click a link in another application to send a mail message, for example, when you click on a mailto link or when you click File -> Send link" in Firefox. Note that the default mail client is not as much of an issue when using Mozilla Suite/SeaMonkey because the browser and mail components are integrated (e.g., a mailto link in a SeaMonkey browser window should open SeaMonkey Mail, regardless of your default mail client).
This article describes how to
configure Thunderbird as the default
e-mail client. However, you must also
configure any other e-mail clients you
run to not attempt to be the default
e-mail client or it will have no
effect. For example, in Outlook
Express you may need to press a button
in "Tools -> Options -> General ->
Default Messaging Programs" to make
the dialog box say "This application
is NOT the default mail handler". Note
that the calendar in Outlook will not
work unless Outlook is the default
You do not need to make Thunderbird
the default email client in order to
send/receive email. It's used mainly
to allow other applications to use
Thunderbird to send a message by
making SimpleMAPI calls (if your
operating system supports MAPI) , or
by your clicking on a mailto: URL (in
a browser). It also associates
Thunderbird with the .EML file
extension under Windows (if you're
running 1.5 or later) so that if you
double click on a .EML file its
displayed in Thunderbird.
Note: If you receive a message such as
Firefox doesn’t know how to open this
address because the protocol (mailto)
isn’t associated with any program.
that means that no mail client is
currently set as the default and you
will need to set one.
In Thunderbird, go to "Tools ->
Options -> General" and select "Use
Thunderbird as the default mail
application". (In the Mozilla Suite,
go to "Edit -> Preferences -> Mail &
Newsgroups" and select "Use Mozilla
Mail as the default mail
application".) If that doesn't take
effect right away, try restarting
Thunderbird or even the computer once.
If that still doesn't work then
another email client (such as Outlook
or Windows Mail) is probably also
configured to be the default email
client. If you're using Windows Vista
go to "Start -> Default Programs ->
Set Program Access and Computer
Defaults" and set "Mozilla
Thunderbird" as your default e-mail
application. See this article at
msdn.microsoft.com for more
If you're running Windows XP another
solution would be to download the
DefaultMail utility and use it to
set the default e-mail client. It can
also do this on a per-user basis.
That's useful if several people share
a machine (with their own Windows user
account) and each wants to use a
different e-mail client as the default
e-mail client. If none of these
methods work it might be because your
windows account doesn't have the
rights to modify the registry. Try
using the "run as" command to
temporarily run a command/application
as a administrator.