You can achieve this by setting up a Campaign Triggered for an action (every time a transaction is made), the respective user will be notified with a newsletter.
You can do this by navigating to Automate --> New Campaign
Configure a Completed Campaign with the Campaign Name you wanted with Start and End Dates of the Campaign and Choose a Trigger ( Transaction)
and Choose a newsletter template which you want to send across to the member when a transaction is made
You can track the emails sent on Automate --> Manage Campaigns and Choose the Campaign you have set
Please note setting up a campaign will sent out a newsletter for all the members who are going through' a transaction not specifically for one particular member