Sending Mail in Sharepoint using code.

we should include the following namespace
for this Add reference of Microsoft.Sharepoint in references.

using Microsoft.SharePoint.Utilities;

Get the header information which contains To,Subject,CC...

System.Collections.Specialized.StringDictionary headers = new System.Collections.Specialized.StringDictionary();
headers["To"] = v-sasikp@microsoft.com;
headers["Subject"] = "This is test mail";


finally,
SPUtility.SendEmail(myweb, headers, emailMsg, false);

But this requires configuration of email server in central administration.

Simple Ex:
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;

namespace blogmail
{
class Program
{
static void Main(string[] args)
{
SPSite Site = new SPSite("http://sasikp-v:4008/");
SPWeb myweb = Site.OpenWeb();
SPUtility.SendEmail(myweb, false, false,"v-sasikp@microsoft.com", "This is test mail for blog","Pls dont reply to this mail this is testmail. ", false);

}
}
}