In Prefs under the Viewing tab, the message threading is checked and the color is light blue. In the view menu outside prefs, the organize by thread is grayed out.


Mid 2010 MacBook Pro 13"
2.4GHz, 750GB SATA HD, 8 GB RAM, OS 10.7.5
1 HDX1500 2TB Ext.HD, 2 HDX1500 1TB Ext.HD
HP Laserjet 6MP printing postscript via 10/100 Intel print server
Netgear WN2500RP Range Extender (Ira rocks!)
Linksys WRT1900AC Wireless Router
Brother MFC-9340CDW Color Laser
iPad Air