start on a message in a mailbox in thunderbird.  tab through the headers you will hear things read normally for example "from foo@bar.com"  but if you then shift tab back through you will here things like "schreader application inbox from foo@bar.com" or "schreder application inbox to: you@baz.com" Fer also states that the ":" in the label isn't actually  present.  It seems like atleast the first issue of "schreder application inbox'being spoken is some sort of issue in how orca gueses the field name since it works in one direction.