Email users are smart nowadays. Your email newsletters are most likely to be ignored if you are trying to hardsell your services. Why?
Everyone knows how to Google or Bing for information. They find product review more resourceful than your newsletter. Well, we are not going to go into details of how you can make your newsletter more productive. That is something you can try and measure on your own.
Yes, what tool to use?
GroupMail is one of the mass mail software you can use. What makes it stand out is the ability to connect to any external database to retrieve an up-to-date email lists.
To do that, you need to install MySQL Connector/ODBC driver. Add a new data source in ODBC Data Source Manager (Control Panel > Administrative Tools > Data Sources). During setup, leave the password field empty.
Next, setup the Database Connection Manager in GroupMail. It is pretty straight forward. Then, setup a new Group and choose Connect via External Database. Groupmail supports SQL query to pull out email addresses you want.