Hi,
If you are using mail merge, try Smass V 1.0 . Smass is free and easy to handle google spreadsheet. You can completely customise it according to your need and share it with your database.
I have developed this tool for everyone to do a free mail merge. It is secure and doesn't require additional add-ons.
You can send emails up to 500 recipients per day through the Gmail website. If you are a Google Apps for Work user, your daily limit is 10000 email recipients per day.
You can access it here: https://bit.ly/SmassV1
Enjoy! Shail Jadav https://shailjadav.github.io/