One way to increase retention is by ensuring customers are as active as possible. If a user has remained inactive for a while, an automated email through your CRM system can induce this user to take action.
For example, if you are tracking how users interact with your product and notice that they have only used a small array of the features, an email explaining how to use other features could re-ignite their interest. Emails could include educational content such as best practice guides or successful case studies from other customers.
This strategy is best aimed at relatively inactive users. Users that are already comfortable and active with the product will not appreciate a barrage of automated emails.