Hi meema, sorry to hear about this problem. The file that stores your download preferences -- which also includes mailto -- should be retained during updates. I don't know why yours seems to be getting flushed or modified.

If you simply click a mailto link (mailto:johndoe@example.com), does Firefox ask you what to do, or does it immediately send the address to your system default mail application?

Thanks for your prompt reply. Narrowing down the issue - my Yahoo email works fine for sending and receiving. However, if I want to email a link, only Outlook appears which I do not use. (yes I know I can cut and paste instead). Before the last 2 months of Firefox updates, I would go to file,settings,applications menu, drop down to mailto, find Yahoo and reset it with no problem. Now I do not find that option - see uploaded image below and I cannot type it into the search window. Can this be remedied or do I just accept that Firefox no longer supports this feature? Again, thanks.

I think out of the box Firefox shows mailto with the choice of your system default or Gmail. I think Yahoo has gone missing from the latest version, but if you had it from an earlier version, it should carry over.

I put a copy of an older handlers.json file on my website at:

https://www.jeffersonscher.com/res/legacy-handlers.zip

You can extract the handlers.json file from the Zip archive and view it in a tab in Firefox to confirm that it doesn't contain anything unusual. Then you can use it to replace the current file which lacks mailto and Yahoo. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > Help > More Troubleshooting Information
• (menu bar) Help > More Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, find the Profile Folder row. On that row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows File Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then:

Right-click handlers.json then Rename to something like handlersOLD.json

Drop the other handlers.json file into the folder.

Start Firefox back up again and check the Settings page, Applications list. Is mailto back?

In the future, you might want to back up the handlers.json file before updating.

Thank you so much for your time and effort in trying to resolve the problem. When this first happened a few updates ago, my daughter walked my through the exact steps which you have outlined for me. Of course, it worked until the next automatic update. So I appreciate your written instructions which I plan to attempt after which I will remove the automatic updates and follow the last of your instruction. Again, thanks for your help.

Hey, I just wanted to say THANK YOU to Jefferson, his solution worked. And i've been combing the internet for about a month to find something that worked for mailto.

One thing I noticed in my profile folder, was I had a bunch of handler.json.corrupt files. So that may be more info for firefox. If they ever check these forums...

One thing I noticed in my profile folder, was I had a bunch of handler.json.corrupt files.

Hmm, I don't know what is causing that. Maybe keep those in a separate folder for future reference in case they are needed for troubleshooting.