Hi CherylMackay
Did you make Outlook your default email program?
To do that save your work and close MS Word, Excel (or whatever you are using). Open Apple Mail, Go to the mail menu and open preferences, choose default email reader, then choose Outlook. Then quit.
Restart your Mac.
Did you start from MS Word to create the merge?
Click on the Mailing's Tab. Click on the "Start Mail Merge" Button on the left but when you click on it use the little down arrow to drop down the select list and choose select Recipients. That will bring in your source. If there is an email address field you will be able to go to the next step. Click on the same "Start Mail Merge" Button but this time choose "Email Message".
Then when you are finished go to the button on the right and choose Finish and Merge - email should be there. Be careful - because it goes right into Outlook and the emails go out. Disconnect from the internet to have them queue up in your outbox.
Hope that helps
More details here:
http://answers.microsoft.com/en-us/mac/forum/macoffice2016-macword/mail-merge-wo rd-2016-for-mac/76374cac-2172-4a1e-8cae-256770b15212?page=2&auth=1
Note – they didn’t specify to restart their Mac, so it wasn't resetting and i think that's what frustrated many of these folks in that post.