Journey builder is a great tool to engage customers with personalized campaigns on the basis of different triggers and conditions. As your users move through different channels at different stages of their journey, journey builder allows you to create unique user journeys based on different actions performed by them.
No matter what medium you are choosing to engage users, Email campaigns are the most primitive and promising medium to engage users. Now, you can imply the condition of email replies when you are choosing the email campaign as a medium to engage users in a journey. With this condition, you can automate the process of engaging with the users who have replied to you.