I can make smtplib send to other email addresses, but for some reason it is not delivering to my phone.

```
import smtplib
msg = 'test'
server = smtplib.SMTP('smtp.gmail.com',587)  
server.starttls()  
server.login("<username>","<password>")  
server.sendmail(username, "<number>@vtext.com", msg)  
server.quit()

```

The message sends successfully when the address is a gmail account, and sending a message to the phone using the native gmail interface works perfectly. What is different with SMS message numbers?

Note: using `set_debuglevel()` I can tell that smtplib believes the message to be successful, so I am fairly confident the discrepancy has something to do with the behavior of vtext numbers.