Not sure but I think it is kind of working now. I just leave it as is, it is the best I can get it.
So thanks a lot everbody ,
Thomas

I guess the accounts for which the mails are only stored on my PC need some more attention?

I think I was a bit to quick claiming everything is wotking.
I fetched some more mails but I still have a from April 2016 till some where in 2013?
Maybe there are more accounts I need to reopen and fetch?
Thanks
Thomas

Hey burnout426 it seems that everything is working out fine here.
Some minor issues with the layout of older mails but I will start importing the other accounts first before worrying about the layout.

Thanks a lot so far
Thomas

And yet some more I tried - logging.
I did add the lines to the accounts.ini as described in the link mentioned above.
Hover it turned out that no .log file was created. Its probably me making mistakes, but it seems to be pretty straight forward. And I can't spot the possible mistake!

And another piece of information if I send a mail from another mail account to myself, the mail arrives at the computer in in received box at the most recent position. Strange is the fact that the focus of the focus bar (navigation bar) is moved to the oldest mail. So I receive the mail but I see the oldest mail instead of the current mail that arrived.

I just recognized another thing some of the mails that should be in the sent folder are put in the received folder, and as a result of that i think the From field is changed to recipient field (my Full name). This is only the case for some mails and only at a random basis. Just now 4 mails are received wrong is the received box but should have gone to the sent box. And also some older mails show the same behavior at random.

Sorry should have checked better before. I had another look and now I found that the test mail is not making it around because it is sitting in the outbox, and is not leaving the computer.

Hey it seems to work burnout426. But a bit strange.
When I cam back from hospital I tried first all setting as they where.
Type:
IMAP incoming server name: imap.ziggo.nl port: 993 TLS: checked username: my email address password: my password
outgoing server name: smtp.ziggo.nl port: 465 TLS: checked username: my email address password: your password
These are the settings you suggested a bit further up. The only thing I did today was to re-enter the password for incoming and outgoing server. Still nothing happened. When I had another look at the kdhtm@ziggo.nl section at the bottom left part of the screen I saw the first option read kdhtm@ziggo.nl and I tried it. This triggered that the mails from the server where downloaded. Mails go back to about the same point they do on the server (checked with webmail). Just at this moment a mail was fetched (autoamtically) without any interaction upfront. When I now send a test mail (adressed to myselfe) from Opera Mail on my computer nothing happens and I cant see the mail any more on my computer or on webmail. Therefore I tried what happens when I send a test mail (to myselfe) from the webmail account. And in that case the mail is received automatically from opera mail on my computer. ??

Thanks for the tips burnout426, I'm currently in hospital as soon as I'm out again I will try your suggestion.