First, please keep in mind that Thunderbird is free. Being free, it depends on volunteers to assist. Volunteers give of their own time as part of the community assist. Most problems can be resolved if enough information is shared. Second, I read your prior post. It was lacking any information that may have opened a window on a possible problem. This is because most problems tie in some way to the email host's requirements. You did not state whether IMAP or POP, or the email host's name, or whether there was more information, such as a recent update or restore. Providing more information allows volunteers to assess the possible problem and whether the volunteer has knowledge on that topic. So, if you will provide some detail on your problem, you may get the support you seek. SO, since I'm here, I'll prompt a bit. Is this IMAP or POP? Did this loss happen with an update? Did you lose all mail or just incoming (or outgoing)? What antivirus do you use? Is this Windows, Linux, or Mac? What version of thunderbird are you using? Knowing this may help. thank you