Start here https://support.mozilla.org/en-US/kb/switching-thunderbird#w_importing-from-outlook-and-eudora

Which protocol (IMAP or POP) do you use with your iCloud Mail account in Outlook 2007? I suppose you meant Windows 10, but not 16, right?

Thank you for your response. The protocol is set to IMAP / SMTP. Yes it is Windows 10 (stupid typo)

So if I understand correctly, I should first install version 31.8 and import the Outlook data and then update to the most recent version of Thunderbird? How do I make the connection for the iCloud data (contacts, calendar and tasks)?

Since you've been using IMAP, your messages and folders are not just in Outlook, but in your iCloud mailbox on the server as well. Confirm if that is the case, by logging in to your iCloud Mail account via a browser. You will not have to import Outlook data using Tbird 31 if that is the case, because the latest Thunderbird v78.x will synchronise the messages and folders exactly the way they are on the server. For contacts and calendar, you can synchronise those with Thunderbird using the TbSync add-on.

Yes, that is correct for my iCloud email account. I also have several other accounts and they have a POP protocol and I also have a folder structure in which I store the mails, and it is this structure that I also want to transfer. So, for the POP accounts I need the Tbird 31 or can this be done directly from Thunderbird version 31.8?

Yeah, for those POP accounts, you'll have to use the old Tbird version to import Outlook data because of the reason given in that article. Make sure you have a backup copy of the Outlook data file stored somewhere safe and convenient just in case. Tbird 31.8 will do just fine. I wrote Tbird 31 just to simplify things, not to imply that you must use 31. I was generally referring to all the v31.x versions, of which 31.8 is one of them.

OK. I have done the import of my POP accounts. The mails and file structure was OK. But the account information is not successful. Do I have to set this return manually?

Yes you do.

All accounts have been adjusted. Update to Tbird v 78.1.1 has been completed. Installation of add-on TbSync has been completed. Where and how can I now sync with iCloud Calendar and contacts? In the tab of the calendar I see the symbol to synchronize, but this is light gray and not clickable.

See https://support.mozilla.org/en-US/questions/1297248?page=2#answer-1338582 for how to use TbSync.

Good morning, I have followed the specified procedure and largely succeeded. Here are some problems: 1) Contacts (address book)

     - No photos of the contacts are visible
     - The labels are in unrecognizable text. (see attached screenshot)

2) Calendar:

     - No birthdays are visible.

Is there only a list form available of the contacts? In Outlook is the possibility to have different representation with tubeness cards, among others. (see 2nd screenshot)

How can this be remedied. Thanks again for your help.

If you connected TbSync to your iCloud Contacts address book and synchronised it with Thunderbird, then what you see in Thunderbird's address book should be matching what you see in your iCloud Contacts address book via a browser, iPhone or Mac. Is that the case? What I see is a screenshot of the contacts in Outlook '07. Was Outlook '07 synching with your iCloud Contacts address book?

1) Yes, Outlook '07 synching with iCloud Contacts. The screenshot was as an example. I also installed the add-on Card Book with the hope that it would be correct, but there are not pictures to see pictures.

2) What do you think of the labels with unrecognizable text?

ICloud Contacts photo sync is known to be problematic even between Apple devices. What does the photo tab for a contact in Thunderbird show, or is it merely empty? I don't know if or how the iCloud CardDav server presents the photos to a CardDav client. Does it present them as public URLs to the photos like Google Contacts does? If so, then the photos would load just fine in Thunderbird.

I don't know why those labels are showing that way. My guess would be locale settings (UI language), seeing as your Tbird is not in English. See if you can find more info here https://github.com/jobisoft/TbSync/wiki

iCould contact photo’s: photo tab in Thunderbird is merely empty. I will try to ask Apple for more information about that topic. If I enter a photo in the Thunderbird photo tab, it will be transferred correctly to iCloud, so ...? So I will adjust the photos manually. I will have to do it twice because the images are not transferred in the add-on "Card Book"

Unrecognizable text: Problem also arises in the English version with the input data from Google. https://github.com/jobisoft/DAV-4-TbSync/issues/225

thanks again for your help,