now a days my mail is full by fraud mails

Me too when I open my mail box, there will be at least a few scam mail that I never want to read at all. Even thought I have turn on the scam filter, but yet it just came in like nothing...I hate it!

You ask where do these people get your mail address. The first thing I would ask is do you receive (and forward) the kind of messages which say "Forward this to 10 of your friends and you will have good luck!" or "If you don't forward this to 10 of your friends in the next five minutes you will have bad luck!" or, sometimes, it's just an "inspirational" message or a warning about a 'virus'. They usually suggest that you should forward the message, anyway. This kind of message gets forwarded many times, gathering hundreds of email addresses on the way (most people don't bother to delete all the previous email addresses). At some point this email gets forwarded to a 'friend' of a friend of a friend who is (although he never says so) a professional email harvester. He extracts all the email addresses (including yours) and sells them to spammers. There is quite good money to be earned by this! Another method of collecting email addresses is from those sites which allow the display of members' email addresses. All of the reputable sites don't do this (and MyLot forbids us to put 'personal information', such as email addresses and phone numbers in discussions or responses) but some sites quite happily display the email addresses of all their members on the members page or in their forums. NEVER sign up to a site that does this! Many spammers have software which generates thousands of email addresses at random. They then just send their mail out to all of these random addresses. Most of them, of course, don't get delivered because the address doesn't exist but some do and if you are unfortunate enough to be one of those people, the spammer KNOWS which addresses the mail was delivered to and will continue sending spam to those addresses. If you use Yahoo Messenger in chat rooms, you should ALWAYS log in with an alternate ID. Never use the one which is the beginning of your mail address. Mail harvesters use chat rooms a lot and all they have to do is add your ID to '@yahoo.com' or something similar and they can send you a mail! The best thing to do with spam email is to allow Yahoo (or whatever mail provider you use) to filter spam messages and any that may occasionally find their way into your Inbox, simply select and 'Mark as Spam'.

To talk about finding mails, it is very easy as when you register to some sites, they ask for your email address and one or a few of them sell to it to these people. To stop them, you will have to contact the website people in which you have an account. For example, if you have an gmail account, then just mail them regarding these fraud mails and then they will block all these mails before entering into your account. Gmail does it for sure and I don't know about other sites.