Over 75% of email being sent through mail servers worldwide is considered SPAM. Unfortunately nothing can be done to completely stop SPAM emails, however 5NINES spam filter should quarantine a vast majority of them.
Always treat email from people or organisations you do not know as suspicious, especially if the email has an attachment or a link to a website. Don't be tempted.
Do not respond to unsolicited email—as it will only validate that yours is a functioning email. This includes clicking on any “unsubscribe” buttons to stop future emails
Never open an unexpected attachment in any email—even if from a friendly sender
Create a filter in your email program to automatically move incoming mail with these types of messages into a junk folder which you can review at a later date for deletion.
Make sure you have the latest anti-virus software installed on your computer. Software providers include AVast!, Norton and McAfee.
Never broadcast your email address on websites—ours or others. There is spyware that scan websites for email addresses and assumes they are valid. Have your webmaster encrypt your email addresses on your website
Anytime you must give your email address over the internet, it is highly recommended that you use a free email account name (i.e., email@example.com).
If it becomes really bothersome, one option is to close down your current email address and make a new email address that you would only share with colleagues, employees, customers and friends.