If you have an e-mail account, there is a good possibility that you are getting a deluge of spam e-mails through no fault of your own. Even if you have never given your e-mail address out, there is a chance that you could be bombarded with e-mails simply through someone sending to a random e-mail address.
Sensible precautions can only protect you so far, so it is a good idea to take advantage of some of the free anti-spam products on offer.
Some of the better and free options to choose from are:
Windows Mail / Outlook Junk Mail Filter - If you use Windows Mail or Outlook you will have the option of enabling the Junk mail filter. This is surprisingly effective and should be the first line of defence if you use one of these applications. It's free and updates regularly via Windows Update.
SpamFighter - Spamfighter has a free for private use version, ideal for protecting your home e-mail. This advanced application tags your e-mail with an advertising line (in the free version), but is worth using if you have real spam problems.
MailWasher - The free version allows you to protect a single e-mail address from spam, however it isn't as automated as some other spam software.
Spamihilator - This is a freeware application that works quite well and can be trained to recognize spam or safe e-mails. Great for a free application.
POP File - Pop File is an open source project that can sort your e-mails quickly (i.e. spam, and not spam). If you are after something free, powerful and configurable then this may be the best option.