Uninstall Thunderbird then reinstall it. This should hopefully re-register it as an email client. Set it as the default email app in Windows 10 Settings, then in Tbird's Options > System Integration and try the mailto links again. Tbird 78 should open the reply (write) window, not a tab instead.

Tried that but no go.

• I uninstalled Tbird 78
• reinstalled it and marked it as the default Mail client
• made sure it was selected as default in the system settings.

Still only get a blank Tab saying loading , see attached image.

BTW am running W10 Pro 2004

CHeers

Nor

You forgot to attach the image.

I tried. let me try again. looks like it took this time.

Why don't you close that tab?

I did but there is no reply window anywhere

Here is what the link looks like in the SOURCE view

<a target=3D"_blank" style=3D"text-decoration: none; color: #337ab7;"=20
 href=3D"mailto:[email protected]?subject=3DRe:%20Rodents%20in%20a%20P=

OD">Reply To Group</a> |

So that tab opens each time you click the mailto link?

YEs and it's blank. However, I just sent myself a simple e-mail with the link <a href="mailto:[email]@comcast.net" > test </a>

And when I received it and click the link it behaved properly. I got a new tab formatted as a reply. Looks like It's something that GROUP.IO is doing to the links that throws a curve at Tbird.

YES and it's blank.

However, I created a simple email to be sent to me that  had a plain mailto link and when I received it and clicked the link Tbird did what it was suppose to. Opened a properly formatted reply window with the e-mail address placed in the TO box.

Perhaps Groups.io is doing something strange?

Nor

Looks like it might be Groups.io doing something to the mail link that's throwing Tbird a curve.

Perhaps groups.io is doing something to the link that Tbird doesn't like.

I'm having a hell of a time posting replies. Hope this goes thru.

YES

I created a simple E-mail with a mailto link in it and when I set that to myself and open it Tbird works the way it should. Perhaps the format Groups.io uses is messing up Tbird?

Just did some testing and it seems the TARGET ="_blank" is what's causing the trouble.

Nor

I sent a test e-mail with a simple href="mailto:" and it worked properly. When I added the TARGET command it fails. Would it be possible to have Tbird ignore that target command?

The target=_blank in a link forces the URL to open in a new tab or window, when it's clicked on a web page. It's unnecessary if the URL is a mailto link, since the action is to launch a new message in the default mail client, not the browser.

Right. I agree. I posted this issue to the group.io group and it seems that its a system wide problem between Tbird 78 and Group.io Mailto: link format.

My thought is that something changed in the New Tbird that broke this. I just checked some of my older e-mails from Groups.io (oct. 2019) and the format of the mailto link has not changed since then.

That kind of tells me that the way Tbird handles the mailto link needs to be revisited.

IF anyone wants a copy of an Email from groups.io I'll be glad to forward a copy.

Let me know if I can do anything to help resolve this. As of now the only way I can reply to group.io is to go to their web site and not use Tbird.

Cheers

Nor

Is your TB 32-bit or 64-bit? If it's 64-bit, do you know if the version that worked OK with these links was 32-bit?

https://bugzilla.mozilla.org/show_bug.cgi?id=1517955

HI My Tbird is 78.4.0 (32-bit). Versions prior to 78 seemed to work OK. I think the last previous version was 64 bit.

BTW am running windows 10 pro 2004

I just loaded Tbird 68.2.2 32 bit on another pc and it handles the MAILTO: properly from groups.io . The email form comes up preloaded with the address and subject as I would expect. However, as I had mentioned before, I get a LOADING Tab in Tbird with nothing in it but that doesn't preclude me from sending the message.

Hope that helps. Nor