A default email client is the client that is activated if there is a mailto: link from a web page; it does not mean that other email clients, when started, do not continue to function normally. On transferring files, TB has an import feature, so it's unclear what you're requesting.

I'm sorry but this doesn't make any sense. what do you mean by "if there is a mailto: link from a web page" ?

A "default" program means a program that will always open unless another program is selected for the specific type of file. That's what "default" means.

I have three or four programs that can open a .jpg file. I have selected ONE of them as the default program. When I open a .jpg file, my default program opens the file - not all 4 programs at the same time.

Likewise, I can select in the Windows settings a DEFAULT program for my mail out of three - Windows Mail, Outlook and TB. Windows Mail doesn't receive my mail even when it's open, so how come Outlook still does?

re transferring Outlook files - I leave it for now. thanks.

Of your several programs than can open a jpg file, if you start them, they are still capable of opening jpg files. I have Thunderbird as a default and thunderbird beta also. Both of them retrieve messages when open, but only Thunderbird reacts to a mailto link. Likewise, I have several browsers, all of which function similarly, but only the default reacts to an HTML link. So, your Outlook client, when started, will retrieve messages.

yes that's true, but mailto: link only opens the default email client when I click on it.

This is of no importance to me as I can always select which email client I want to use to send an email from.

My issue is about receiving emails , as I'm getting them to both Outlook and TB, while I want to transition from Outlook completely and close it. Sorting out and importing my emails is a huge job which will take me few weeks - that's not something I can do in one hour.

And this job is getting bigger with the new emails I receive to Outlook every day ( I have several accounts business and personal), as I will need to sort out which of these emails I already have in TB and which I do not to avoid duplication (the starting date is not enough).

In this case I need to disable my email accounts in Outlook.

Okay, as I understand it, you are already receiving messages from Outlook in TB. Are you not able to stop Outlook from running? That seems the immediate need.

I didn't close Outlook as I'm still accessing my emails in the folders there, but I have removed my accounts from it to stop receiving emails.

This may seem like an obvious immediate action; but I wanted to test TB first as I've never used it before, whether it suits my needs.

Now I can focus on sorting out my emails there (delete, archive, export to TB).

so for now, the issue is closed. thanks