Check out this Office support article explaining how to use Outlook 2013 for a mail merge. I created the list in Excel and it worked great!
https://support.office.com/en-ie/article/Use-Word-mail-merge-for-email-0f123521-20ce-4aa8-8b62-ac211dedefa4?ui=en-US&rs=en-IE&ad=IE
Kathy Van Pelt