In the "Options" section of WLM use the "Spelling" tab and check the box at the top "Always check spelling before sending." Also, if you just want to correct the email spelling but not send the message try the "F7" function key while composing. (In the 2009 version of WLM there is also a "Tools>>Spelling..." choice in the menu bar of the main window of the new message.)
My Computer
Computer type
PC/Desktop
Computer Manufacturer/Model Number
OQO 2+
OS
Windows 8 Pro w/MC 32-bit
CPU
Intel Atom 1.86 GHz
Motherboard
OQO 2+
Memory
2 GB
Graphics Card(s)
Intel GMA 500
Sound Card
IDT
Monitor(s) Displays
LCD
Screen Resolution
800 x 480 (portable) 1280 x 1024 (docked)
Hard Drives
64 GB SSD
PSU
9 Ah Battery (portable) or OQO Brick (docked)
Case
Shirt Pocket Sized
Cooling
Tiny Fan
Keyboard
Slide out (portable) DiNovo Edge (docked)
Mouse
Eraser head (portable) Logitech Bluetooth (docked)