My girlfriend has an email account with ~10k messages, of which ~700 were unread. Today, while using Thunderbird, she accidentally hit the keyboard shortcut for "Mark as Read by Date", which changed all her messages to read. It's not feasible for her to manually change those ~700 messages back to "unread". Is there a way of making Thunderbird mark those messages as read again? One thing that occurred to us is for her to select all the message that were changed from unread to read today, then mark all of those as unread. Is this possible. Thanks! Nate