Broadly categorized, spam includes unsolicited advertisements, hoaxes and the proliferation of malicious software–malware. The inconvenience and danger to the user is increased by the fact that the costs of sending email are next to zero, and authors of spam have many tools and sources available to acquire new email addresses.
In addition, the volume and variety of spam makes it very difficult to regulate. The longer you use your email address, the higher the possibility of it ending up in a spam engine database.
Some hints for prevention: