Is Yahoo Mail your default mail client? If it is, go to Start>Default Programs and make sure you have it set correctly.

No, but it never has been. My other PC has Firefiox 5 running with Yahoo Mail ok and Yahoo Mail isn't the Windows default there either.

I'm talking about the setting within Firefox itself: Firefox Options -> Applications -> Mailto -> Application Details: Here you get an option to remove applications from the list. I removed Yahoo Mail, now I want it back.

Sorry to be so long. I've been away. In your applications click on "Mail to" and it will show your default email. Click on the little drop arrow and it will show you the usual web mail alternatives including Yahoo.

This will help with possibilities and procedures -

https://support.mozilla.com/en-US/kb/Changing%20the%20e-mail%20program%20used%20by%20Firefox?s=mail+to&as=s

This is where I deleted Yahoo Mail, it no longer appears in the drop down - see image below.

I'm afraid you'll need someone else's help.

Is the about:config entry for Yahoo the same as G.Mail and Hot Mail?

This will take you back to Page 1.

Help anyone?

You have to add your preferred email client to the Internet Options menu like this:

1. Open Microsoft Internet Explorer and then click Tools and go to Internet Options.
   
   
2. Click the Programs tab and where you see "Email", choose your email client.
   
   
3. Remove the checkmark from where it says "Tell me if Internet Explorer is not the default browser" in the same menu.
   
   
4. Click Apply/OK and close Internet Explorer.
   
   
5. Next, start Firefox and click the orange Firefox button, go to Options | Options | Advanced.
   
   
6. In the General tab, System Defaults at the bottom, checkmark the option: "Always check to see if Firefox is the default browser on startup" and then click the "Check Now" button.
   
   
7. Click OK, close Firefox and then restart it again.

You should be able to see Yahoo as an option in the Applications panel.

You can open the about:config page via the location bar and do a search for mailto via the Filter at the top of the about:config page.
You can reset all mailto related prefs via the right-click context menu to their default values.

What should work is opening Options > Applications, clicking the item beside "mailto", selecting from the menu "Use other", then browsing to the application you want to use and choosing it. That item should then appear in that list. Choose it.

Thanks for the effort guys but none of these help:

Xircal - It's nothing to do with the Windows default as explained earlier.

cor-el - I've already checked the about:config as explained earlier, Yahoo Mail is set correctly there.

finitarry - That would work if I was using an application but Yahoo Mail is a web app and so you can't browse to it.

So, you have a prefs with the value to open Yahoo mail?

• http://compose.mail.yahoo.com/?To=%s

Did you also check the other mailto prefs (network.protocol-handler) ?

Set the pref gecko.handlerService.allowRegisterFromDifferentHost to true on the about:config page.
Run this javascript code via copy and paste to the location bar and press the Enter key to run the code.

javascript:navigator.registerProtocolHandler('mailto','http://compose.mail.yahoo.com/?To=%s','Yahoo! Mail');

Do not forget to reset the pref gecko.handlerService.allowRegisterFromDifferentHost to false after you have added Hotmail.

(corrected javascript coded - C)

Great job cor-el! Problem solved with your instructions only I had to put "Javascript: " in front of the line of code you gave me otherwise the location bar just ran a search. So the final solution is:

1 - Set the pref gecko.handlerService.allowRegisterFromDifferentHost to true on the about:config page.

2 - Copy the code below into the location bar and press enter:

javascript: navigator.registerProtocolHandler('mailto','http://compose.mail.yahoo.com/?To=%s','Yahoo! Mail');

3 - Set the pref gecko.handlerService.allowRegisterFromDifferentHost to false on the about:config page.

ok cool it kinda works but everything is in the To: part of the email. subject and everything. For example the to: has "mailto:sale-c3e9m-2523143464@craigslist.org?subject=xxxxxxxx (city)" I cant figure that out. Any ideas? Thanks!

I had the same problem after I removed Yahoo! Mail and tried to replace it. When I performed all of the steps you laid out with the javascript line, Yahoo! Mail was still not listed as an option to set up under mailto. I am running FireFox 6 and even tried unistalling and reinstalling without success (running Windows 7).

Any other ideas?