Techniques for auto email

I need to be able to send an automatic, unattended email to an external address during login, or at scheduled times. The email needs to include the output of a command line (specifically ipconfig, to obtain the changing dynamic IP address).

I canuse mailto:email_address... etc but it won't actually send it, just pop it up ready to send.

Is there a good command line tool from MS or 3rd party to do this e.g. sendmail on unix.