Hello, since you're using the ASP.NET technology, don't waste time doing C# base things. ASP.NET was developed over .NET Framework to help you write less C# code and do more on the Internet.
You can use the ASP.NET codes to send the emails using any email service provider to any recipient on the internet. You can just use the username and password that you get from the email service provider. Basic example of this provider is Google Mail (Gmail) or Outlook, you can use any of them and just pass the username and password of yours to the ASP.NET (along with some more parameters and properties) and your email will be sent using one line code.
The code is really very simple, I have already covered this in the Article,
Sending emails easily using ASP.NET helpers
Feel free to read it, and you will learn how to send the emails using ASP.NET C# code. It is really very helpfull and easy to send the emails using ASP.NET
class instead of using the old C# email sender.