Email spam is basically unsolicited mail in an electronic form. It tends to involve nearly identical messages sent to many different recipients.
Junk email can clog your inbox and waste your time as you go through all the unsolicited email to get to the important messages. There are several things you can do to reduce the amount of spam that makes it into your email inbox.
Filtering by Content
One way to reduce a significant amount of spam email is to filter it by word. Many spam emails are about certain products such as medicine meant to increase a man's sexual abilities. You can filter emails with those words or emails of a certain topic which you know you'll never or rarely receive legitimate information about.
You can filter the messages you receive to blacklist certain IP addresses of common spammers or Internet hosts that shouldn't be sending external emails.
Avoid Email Harvesting
Do not put your true email address on lists and forms if you don't have to. This reduces the chance of spammers accessing your email and buying it from other spammers in a process called email harvesting. If you have your email address on your personal, professional website, online corporate directory or something similar, do not post the entire email in the form that it's used to send the message. Place extra spaces or instead of putting the @ symbol write (at) then your domain name. Most people will know to plug in the right symbol when it's time to send an email. Doing this reduces the chance of spambots finding your email address online.
If clients need to contact you online, contract forms may be your best option to reducing the amount of spam you get. Users never see the email address and instead fill out the form in the web browser which will send the info the email address you've set it to. The downside to contract forms is that they tend to be inconvenient for users and if they're guaranteed not to get a response from you if they unintentionally misspell their reply address.
Disable HTML in Email
Disabling email HTML reduces the chance of being exposed to offensive images in some spam since the file automatically goes to the spam folder. It also reduces the chance of exposing yourself to web bugs which allow the user to see if an address is valid and if it made it through spam filters.
Use Disposable Email Addresses
Create a temporary email address you can delete if you choose or which forwards email to a real account. These work when you're required to provide an email address for a site you would like to see but have no guarantee that the site won't be used to send you unsolicited emails. Disposable addresses can be manually disabled or set up to expire after it receives a certain amount of messages.