An Electronic Mail that you all know is a better and fastest mean of communication.To implement intuitive , efficient and useful Emails we need to control spams / virus mails. For a mail administrator its too much tough to control spamming mails. There are many organizations like SpamHaus which help in controlling spams.
By watching the below statics you can see the spam mails being attacking a mail server. it shows of 80000 mail transaction the Mail server need to block 40000 spam mails.
To Understand spamming we need to understand how can a Email used to be spamming.