I have seen lots of questions with the opposite tack. If there is already an answer here, I apologize for not finding it and asking again. I support a small business. The main email address is office@<mydomain>.com. Three of us monitor that account, on three separate computers. We have always struggled with not knowing if one of the others already responded to an email or not. This has led to us either spamming the person submitting the inquiry, or all of us "ignoring" it by assuming someone else responded. Is there a way for Thunderbird to monitor and indicate if the email was replied to on any of the systems, not just the one we're sitting in front of? We own the domain and host our email server through inmotion hosting, which gives us lots of control if something needs to be configured server-side.