smtp host for round cube.

I made a web application where when the admin creates a user credentials, after creation, the application will send an email to the just created user credentials informing his/her username and password. 

 

I was able to do this using the gmail, but, I want to use the company email address as the sender. 

 

if smtp.Host = "smtp.gmail.com"; is for gmail, then what is for the round cube?

 

Thanks in advance.