You can send SMS text messages to email addresses as detailed below. Each message will be chargeable as an outgoing text message, even though it is being sent to an email address.

Press Menu, scroll down to Messages and press Select
Press Select (Create message)
Enter the recipient’s email address, followed by a space, and then type your message (using the number keys to select letters – max 160 characters – for the ‘dot’ press 1; for the @ symbol press 1 twice, and for the space press 1 four times)
Press Options
Press Select (Send)
Press Add (New Recipient)
Press Select (Enter Number)
In the ‘Number:’ box, enter *2 and press OK
Scroll down to highlight the *2 and press Send