Email spam lists or often created by scanning Usenet postings, stealing internet mail list and searching the web for addresses. One particular nasty variant of email spam is sending spam to mailing lists. Because mailing list limits activity to their subscribers, spammers will use automated tools to subscribe to as many, mailing list as possible. They then use the mailing lists as a direct target for their attacks. Never reply to spam, this let spammers verifies that this is a known good address. Be careful where you place an email address on the web, so it is not machine readable.
In addition to wasting people’s time with unwanted email, spam also eats up a lot of network bandwidth. There or many software developers who have taken it upon themselves to fight spam with a variety of techniques but because the internet is public, there is really little that can be done to prevent spam or junk mail. However, some online services have instituted policies to prevent spammers from sending spam to the subscribers. With this in mind you should always use junk mail filters and refrain from opening or responding to unknown and unfamiliar emails. Not only could they be just spam but they may also contain a virus, or Trojan which may be a bigger threat to your computer and cost more money in the long run.