Rated 3 out of 5 stars

le khelmsch_de ar Márta 9, 2010 · buan-nasc

Answer (fdservices & others):
an update to TB3.0 would be nice.
By pushing only ctrl-u you can get the message source ... and at the beginning you will see the complete message header!

By the way: an additional advantage is that the message remains UNREAD. That's useful for spam & junk.