Fix what? You have shown us nothing. I ran a test with hotmail and it appears to work for me. see screenshot

https://sites.google.com/view/new-sites-testing/links/mailto-link

mailto:dummyname@gmail.com?Subject=Hello%20world!

I will explain so even you can understand.

I have email provided by Verizon (my ISP), so my address is abc@verizon.com. However, Verizon requires that I use AOL mail as the email platform.

My problem is that under Firefox the mailto function does not work correctly with AOL email (web version). I can identify AOL under Firefox but the mailto function simply opens the AOL link showing the default view. The goal is when you invoke the process to mail a site you are currently viewing, Firefox should open a new email in AOL Mail’s compose window with the site link in the body -- it simply opens the desktop email client.

This is defined in Firefox under settings as follows: 1. Open Firefox’s Handlers settings

2. In Firefox’s address bar, type:

  * Scroll to the section Applications.
  * In the search box, type mailto — you’ll see “mailto” appear as a content type.
  * In the Action column, click the drop-down.
  *  By default, you’ll see options like:

3. Always ask

   * Use Gmail
   * Use Yahoo! Mail
   * Use AOL Mail
   *  Use other…

I selected use AOL email, but when I attempt to use the mailto function is simply opens my AOL email. It should open, and compose a new email with the subject defined and the URL of the web site I am viewing in the body.

For that to occur, you need the string "mailto","https://mail.aol.com/d/compose/?to=%s#newtab","AOL Mail"); The current settings of Firefox lock the capability to modify that string.

I have attempted to modify the uriTemplate value as follows: "mailto": {

 "handlers": [
   {
     "name": "AOL Mail",
     "uriTemplate": "https://mail.aol.com/webmail-std/en-us/suite#/compose?to=%s"
   },
   ...
 ],
 "default": "AOL Mail"

}

As that capability is locked, my issue is how can that be modified. Ideally, selecting the AOL Mail as an option under the mailto settings should produce correct code, and it does not. There are not any screen shots which would further clarify the issue -- try AOL Mail as an option and view the string and the issue will be obvious.

Please escalate as needed as there are many customers who use Verizon as their ISP and have been forced into this model.

Thank you.

Firefox doesn't include an AOL mail option. Most users likely added it by clicking a button on an extra toolbar that sometimes appears when you visit a mail site. The bar asks something about adding the site as an application for sending mail. Usually that's a one and done, but it sounds like it stopped working at some point (recently?).

The problem is that there's no simple way to delete or update the URL string after you save it. It sounds like you discovered where the string is saved, which is in the handlers.json file in your currently active profile folder.

... you need the string "mailto","https://mail.aol.com/d/compose/?to=%s#newtab","AOL Mail"); The current settings of Firefox lock the capability to modify that string. I have attempted to modify the uriTemplate value as follows:

"mailto": {
  "handlers": [
    {
      "name": "AOL Mail",
      "uriTemplate": "https://mail.aol.com/webmail-std/en-us/suite#/compose?to=%s"
    },
    ...
  ],
  "default": "AOL Mail"
}

As that capability is locked, my issue is how can that be modified.

• Open your currently active profile folder (see: Profiles - Where Firefox stores your bookmarks, passwords and other user data)
• Leaving that Windows File Explorer window open, exit out of Firefox
• Make a "just in case" backup copy of the handlers.json file (for example, right-click > Copy, right-click > Paste)
• Right-click > Edit or right-click > Open With the handlers.json file in your preferred plain text editor
• Carefully replace just the content in the quotation marks for the uriTemplate
• Save and close

When you start Firefox, it should read the file and use the new strings. If you notice that the list on the Settings page is wrong, that could indicate a stray character was introduced into the file.

Any luck?

As for the future, Mozilla has a product suggestion site at https://connect.mozilla.org/. If you have time, I think it would be a good idea to post this request there to get into the current feedback stream. Use the "Ideas" section of the site (at https://connect.mozilla.org/t5/ideas/idb-p/ideas).