There are certain situations when you need to use the “reply all” button. In other situations, you should only use the reply button to acknowledge the sender. Hitting the “reply all” button can make you look unprofessional, especially if the reply was only intended for the original sender.
Sometimes, email is not the appropriate place to revise documents, comment on a project initiative, or pose a question. Many firms use the comment feature in word processing programs and forums to answer “corporate” questions. Sometimes, checking the comments in a word processing document can help answer questions about a current project that is frequently making the loop within company email.