Hi bobaloisi13, are you opening the "compose" window in Firefox (on https://outlook.live.com/) or in the separate Microsoft Office Outlook application?

For webmail sites, I think a mailto: link is always going to trigger a new Firefox tab (or new window) rather than switching to the current one. You may need to close the extra tab yourself after finishing your work on the new message.

For the Outlook application, you might check with Microsoft on whether there is a setup issue with Outlook.

hi, i thought it might be an outlook issue but when I do the same thing using Chrome i don't get a second instance of outlook. same is true using Edge.

When you are working with an external mail app, Firefox usually uses the command found in the Windows registry. Usually it doesn't have its own method. However, in case some gibberish was stored in the settings file, you could have Firefox regenerate it to restore the default data. Here's how:

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

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

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows 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 rename handlers.json to something like handlersOLD.json. If you see a file named mimeTypes.rdf, rename that one to mimeTypesOLD.rdf.

Start Firefox back up again. Any improvement?

hi, that fixed it, thank you.