The web can be a dangerous place if you are not careful. Along with many other problems, spam is one of the most common ones. The problem is started by robots (programs on a mission to collect data) searching websites for emails. These robots retrieve any emails they find and send them back to their owner's database(s) to expand their spam marketing campaigns.
If you've already published your email online and you're receiving spam, there are a few options available to help you filter out those unwanted emails.
Here's some common tips to help prevent, reduce and fight spam
Do not publish your email on any websites.
use secure forms that users can fill out to contact you.
use an image of your email, if you must display it.
Use a hard-to-guess password for your email(s) as a security precaution.
Close any open relays on your hosting/server (ask your host admin. or IT guys).
Refrain from subscribing to newsletters and such with your business email.
Forward any spam you get to the rightful authority, or