In email marketing a soft sale means that the initial contact with a potential customer (or first remarketing contact) uses a gentle, service-based tone. It is a clear and direct action in relation to a specific user experience.
Example of Soft Sell
Soft selling is often used on online retail when customer abandons a shopping cart. In this example, the customer may have abandoned for any number of reasons. Instead of pushing the sale, you could inquire using a soft sale tone email message to ask if there was a technical problem you can help with. This opens the lines of communication in a non-intrusive way.