Thunderbird or Earlybird will not open new messages in tabs

tjm1120 Posts 1 Registration date Monday August 8, 2016 Status Member Last seen August 8, 2016 - Aug 8, 2016 at 01:59 PM
I am a long time user of Eudora and loved the folder tabs to open when new emails are received. I have tried every option in Tools - Options - Display - Advanced, Open messages in A new tab/window or existing window and none of the options have any effect.

Any ideas??? - Thanks!!!