blackberry 7520 text messages

How do I send a text message from my phone; In place of a phone number it looks like I need to use an email address. I was speaking to a nextel assistance and she told me that she was going to email me the instructions for sending a text message; but never did. She said that it's there phone number and something else depending on the cell phone provider, before I hung up.

http://www.notepage.net/smtp.htm lists the SMTP mail address format for almost all cell phone service providers

thank you, this was just what I was looking for.

Yeah Nextel's Customer Service is a joke when it comes to this. I had to call 4 times before they actually sent out the email.