Yet Another Mail Merge lets you send your mail merge to one or more Google groups. Read this article for more details.
How to send a mail merge to a Google group?
info First time using YAMM? Learn more: Send your first campaign with YAMM
List your Google groups row by row in your spreadsheet (and some optional information like their names etc.), just like any other email addresses.
Then click Send emails.
How is my campaign tracked?
Every time a group member opens the email, YAMM automatically records it as EMAIL_OPENED.
warning As there is only one email address (Google group) per row, YAMM can't track who exactly opened your email.
How will my quota be deducted?
Sending an email to one Google group reduces your quota by 1, regardless of the number of people in the group.