Systems, methods, apparatuses, and software for network messaging systems in computing environments are provided herein. In one example, a networked messaging system is provided that presents a message to a user, the message being associated with a conversation thread comprising one or more members and having a file attachment. The networked messaging system receives a reply instruction issued by the user to reply to the conversation thread with a modified version of the file attachment, and responsively establishes a reply message associated with the conversation thread that includes the modified version of the file attachment. The networked messaging system transfers the reply message with the modified version of the file attachment for delivery to the one or more members.