The mail merge function in Microsoft Word is powerful but has limitations. It isn't well-equipped to deal with mail mergers, which can cause problems. To send out mail merges, you must use Outlook as your default email program while generating a mail merge on a Mac. Otherwise, you may face Mail merge on mac not working issues using the Merge to Email function. You can change your default email software in the Mail app's General Preferences. You must also alter the default mailer configuration. Make sure Outlook is set as the default mailer, not the "Windows 10 mail feature." Ensure you're using the most recent/identical versions of Outlook and Word.