This workaround will guide you to show the custom fields in the Outlook folder whose items you will export, and then copy all items in this folder to an Excel workbook.

This workaround will take exporting emails from a mail folder for example.

1. In Outlook, open the folder whose items you will export, and click View > Add Columns. See screenshot:

2. In the opening Show Columns dialog box, please do as follows:
(1) Select the User-defined fields in Inbox option from the Select available columns from drop down list;
(2) Click to highlight the specified custom field you will export with in the Available columns list box;
(3) Click the Add button;
(4) Keep the new added column selected in the Show these columns in this order list box, and click the Move Up or Move Down buttons to change its order.
(5) Repeat above (1)-(4) to add other custom fields as you need, and click the OK button.

3. Now custom fields are added in the mail folder. Please click View > Reading Pane > Off to turn off the reading pane.

4. Please select all emails in the mail folder, and then press Ctrl + C keys together to copy them.

Note: You can select all emails with clicking the first one, and then pressing the Ctrl + Shift + End keys simultaneously.

5. Launcher Microsoft Excel, select the first cell in a new worksheet, and press Ctrl + V keys together to paste the emails, and then save the workbook.

So far, all emails in the specified mail folder have been exported with the specific custom fields to Excel workbook.

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