By enabling SMTP on the Lotus NOTES, you allow the Lotus NOTES to route SMTP mail from your application such as asp.net any of your .Net application.
First put in a fully qualified internet name on the server document. Assuming the server name is mr and the mail domain we want to route is blogspot.com, you can put mr.blogspot.com as shown below:
Next enable mail routing (if it is not already done). Enable TCP/IP (it may differ if your Lotus NOTES network is named differently).
Then just get your router to refresh its config by typing the following command at the console:
Tell Router Config Update
Now your notes server can act as a SMTP server for your application