The Sales Inbox will display any new inbound emails or email replies, as long as the emails are from a contact record that you currently have inside the system. In addition, the notification bell in the upper right-hand corner of your screen will display inbound emails and replies as well.
To view replies specific to a sequence, the Sequence Stats and Sequence Enrollment tabs inside the sequence will provide this information.
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For a more detailed walkthrough of this process, please see the video below.