Windows 10: Click on a link in E-mail, Firefox opens a new instance instead of tab

I'm in the process of moving from SeaMonkey Suite (browser and E-mail) and it's been painful so far but I'm getting there.

The stopper now is Firefox. When I click on a link in my E-mail client (eM Client) or a Internet shortcut on my Desktop or in a folder, Firefox opens a new instance of the browser instead of opening a new tab. This completely destroys the flow of trying to follow notices from here or any forum.

I posted a question on the Mozilla Firefox forum but trying to even navigate there is a painful experience.

Anyone have any idea on how to fix this?

I've got eM Client working pretty good now for both myself and my wife but the browser part is a killer. I can switch to Edge and see how that handles it but after spending 4+ hourse getting Firefox setup sop it's usable I'd sort of like to stay with it if possible.

Hoping someone here has some ideas.

:)

 

Firefox opens new browser instance instead of using active one

Out of a sudden (it feels like it started with version 67.0), whenever I click a link in a program, Firefox opens a new instance of Firefox instead of just loading the link in a new tab of the already opened Firefox instance.

I'm not aware of having changed any Windows or Firefox settings, and I couldn't find any that may affect this behavior... I'm running FF with a user-defined profile folder (--profile "c:\mydir"), while new instances are opened with the 'default profile' which is annoying.

Is there a way to fix this?

 

Mail app and web page links not opening new tab

This is probably something dumb I've done, but I can't figure it out.

emails in Mail used to open web links (http and https) in a new tab in my FF browser. Now, they open on the current tab. Not sure whether it's a Mail setting or a FF setting; both have been updated, so either could be the cause.

Any suggestions on where to look for how to handle links in email in Mail?

Thanks!

 

Mail app and web page links not opening new tab

In FireFox: