Here are some Major Phone Carrier Company examples of how to format an email to go to someones phone as a SMS Text Message.

[10-digit phone number]@message.alltel.com
 Example: 2125552555@message.alltel.co
 
 AT&T Wireless (now part of Cingular)
 [10-digit phone number]@mmode.com
 Example: 2125552555@mmode.com
 
 Boost Mobile
 [10-digit phone number]@myboostmobile.com
 Example: 2125552555@myboostmobile.com
 
 Cingular
 [10-digit phone number]@mobile.mycingular.com OR
 [10-digit number]@cingularme.com
 Example: 4152555555@cingularme.com
 
 Nextel (now part of Sprint Nextel)
 [10-digit telephone number]@messaging.nextel.com
 Example: 7035552555@messaging.nextel.com
 
 Sprint PCS (now Sprint Nextel)
 [10-digit phone number]@messaging.sprintpcs.com
 Example: 2125552555@messaging.sprintpcs.com
 
 T-Mobile
 [10-digit phone number]@tmomail.net
 Example: 4252555555@tmomail.net
 
 Verizon
 [10-digit phone number]@vtext.com
 Example: 555255555@vtext.com
 
 Virgin Mobile USA
 [10-digit phone number]@vmobl.com
 Example: 5552555555@vmobl.com