Using the Send Test button in your email message allows you to send a test copy of the email so that you can test to make sure it works and looks correctly. However, the merge Fields contained in the email message do not have their content updated accordingly with data designated by the merge Field.
Test messages do not display merge field data. Instead, the program includes placeholders where the merge data will appear in the final message. To test merge fields, select the test list in the To field and then select Send final.