Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

mailto app isn't working

  • 37 replies
  • 5 have this problem
  • Last reply by jscher2000

more options

when i click on an email my email opens which is ATT but its on yahoo server so my yahoo mail after it opens the email address that i clicked on doesn't appear in the TO space when i had this problem last time i posted on here but those steps didn't work this time by going into about:config changing the email to

Chosen solution

Here is a URL that should work, but it needs to be customized for your particular Yahoo mail server:

The bolded part needs to be edited to match your mailbox. Please try this:

(1) Select and copy the following line of script

navigator.registerProtocolHandler('mailto','','Yahoo 2014'); 

(2) Open your Yahoo mail and then in that tab, open the Web Console using one of these methods:

  • Ctrl+Shift+k
  • "3-bar" menu button > Developer > Web Console
  • (menu bar) Tools menu > Web Developer > Web Console

A small area should open below the current page.

(3) Paste the script next to the caret (>>) and edit the server address to match your specific mail server. This must match or Firefox will block the script.

Then press the Enter key to execute the script.

An infobar should open at the top of the page. Click "Add Application". You now can close the Web Console using any of the same methods you used for opening it.

If instead of an infobar the Web Console displays "Not allowed to register a protocol handler for mailto" then you may need to switch a setting in the about:config preference editor. More below the break.

(4) Test, for example:

I see a long delay of what seems like 5 seconds or so before Yahoo displays the compose screen with that address. I don't know why it takes so long.


(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste mailto and pause while the list is filtered

(3) If the network.protocol-handler.external.mailto preference is bolded and "user set" to false, double-click it to switch it to true.

Read this answer in context 👍 2

All Replies (17)

more options

nope that didn't work i got undefined DARLA notice 510 no element

more options

Sorry, whatever Yahoo's new method is, I am not aware of it.

more options

I posted in the report bug forum it seems there are a lot of users with the issue

more options

i want to make sure i did everything right i entered navigator.registerProtocolHandler('mailto','','Yahoo 2014'); into caret and changed mg4 to mg205 thats what my url shows so i changed it

more options

Hi la321, when you run the script (paste, edit server name, press Enter to submit it), does Firefox display any error message in the Console?

more options

i entered this i changed the url like mentioned but i get a sorry bad request

i entered this in caret navigator.registerProtocolHandler('mailto','','Yahoo 2014'); i get undefined and no element DARLA notice 510 then there is a number 2 in red
more options

I also get "undefined", but I think that is because I already added that handler. If I make a modification to the URL, then I get the push-down between the toolbar area and the page asking whether to add the application. For example, adding &TEST into it:

navigator.registerProtocolHandler('mailto', '', 'Yahoo TEST');
more options

that seems to have worked i got the same popup and i am able to click on a clickable email address when the email appears it appears in red with mailto beside it

more options

how do i get the email address in red removed? when click on an email address it opens up in yahoo as red

more options

I'm not sure what you mean. In the "To" box it appears in red? That might have some meaning in Yahoo! mail, for example, it is an existing contact, or it isn't an existing contact. I don't use Yahoo! mail regularly, so I'm only guessing.

more options

in the TO box the email address is red after i have clicked on a clickable email link on a website

more options

Maybe Yahoo thinks there is a problem with the address. Does it look incomplete or incorrect??

more options

it does it to all email addresses the email is correct but it has mailto: then the email address all of it in red

more options

in the TO box it has it like this this is an example then that is in red

more options

Thanks. The mailto: part is supposed to be removed. I guess you'll need to remove it by hand until we figure out what's going wrong there.

more options

Is there a fix to this yet? my issue has started back again

more options

Hmm, yes, I don't use Yahoo! mail very often. My "server specific" mailto isn't working any more at all.

If you go into Application preferences and change mailto to "Ask me every time" and try again, do you still have the "old" Yahoo! entry that comes with Firefox? For me, this one works after a long delay, i.e., your Inbox appears, then if you count to 5, your new email compose page appears.

If you no longer have that one, here is how you can re-add it.

General overview:

  • Switch preference so you can add a handler from a domain that doesn't match the address bar
  • Run a script using the web console, click the button to add the handler
  • Switch the preference back

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box that appears above the list, type or paste hand and pause while the list is filtered

(3) Double-click the gecko.handlerService.allowRegisterFromDifferentHost preference to temporarily switch it to true

(4) Select and copy the following long line of script (ignore the fact that the forum makes part of it clickable):

navigator.registerProtocolHandler('mailto', '', 'Yahoo Compose'); 

(5) In your mail tab, open the web console using either:

  • Ctrl+Shift+k
  • "3-bar" menu button > Developer > Web Console
  • (menu bar) Tools > Web Developer > Web Console

(6) Paste the script on the bottom line next to the caret (>>) and press Enter to run it. An infobar should push down between the toolbar area and the top of the page allowing you to add an application.

You can test using this link:

(7) Finally, back in about:config, double-click the gecko.handlerService.allowRegisterFromDifferentHost preference to switch it to false. You're done with this tab.


  1. 1
  2. 2