If you have an Excel file with contacts from another email account (how to export contacts to a CSV file), you can import them to Outlook. If the file format is CSV file, you can directly import, but if the file is an Excel file, you would need to save it to CSV file first.
To save the Excel file to CSV file:
Step 1: When the file is open, click the "File" from the Ribbon;
Step 2: Click "Save as" from the list;
Step 3: Browse to the location where you want to save the CSV file;
Step 4: In the "Save as type" box, select "CSV (Comma Delimited)" type;
Step 5: Click "Save" at the bottom.
To Import CSV file to Outlook:
Step 1: Click "File" tab when Outlook is open;
Step 2: Click "Open&Export", then click "Import/Export";
Step 3: Select "Import from another program or file" in the new window, and click "Next";
Step 4: Select "Comma Separated Values", and click "Next";
Step 5: Browse to the file with the contacts and click "Next";
Step 6: Select "Contacts" folder, and click "Next";
Step 7: Click "Finish" in the new window.
Note: You may need to click "Map Custom Fields" to map the variables in the file and the variables in the Outlook.