How do I determine the actual email address of a sender when they are using a fake email address that prevents message filtering? I have been using message filtering for years, but one email address never gets filtered. My filter is set to move the message to the junk folder. I have also filtered by using portions of the email address and using the "contains" option. AOL has a "details" link that allows me to see the actual email address of fake email addresses, so I hope Thunderbird is at least as capable as AOL. P.S.: Why doesn't Thunderbird allow blocking emails instead of this laborious filtering method that takes hundreds of filtered emails for it to learn? AOL does.