Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Import Outlook Contacts to Mac Mail
Instead of populating the Address book in Mac Mail anew, you can transfer the contacts from MS Outlook right into Mac Mail. Follow these steps:
1. In MS Outlook, click File, Import and Export.
2. In the Import and Export wizard, select the Export to a file option.
3. Select the Comma Separated Values file and save the file to any location you like.
4. In Mac Mail’s Address book, click File, Import, Text file.
5. Add the CSV file you’ve exported from MS Outlook.
6. Select the Ignore first card checkbox.
7. If you don’t want to import specific columns of the Address book, select the Do not import option for them.
8. Finally, select the columns you’d like to import and click OK.