Sometimes, you will encounter a pop-up message “Provider cannot be found. It may not be properly installed” when you import .xlsx file (Excel 2007, or Excel 2010) into 1and1Mail Address Book or Multi Account Manager.
Cause:
Your OS does not have the library to decode .xslx file.
Solution:
1. Install the new Microsoft library (Data Connectivity Components) from http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=23734
2. Save your .xlsx file as .xls file (Excel 97 – 2003 format) and then import the .xls file.
3. Save your .xlsx file as .csv file, and then import the .csv file.