Spam is considered to be electronic junk mail or junk newsgroup postings. Some people define spam even more generally as any unsolicited email. Spam is generally email advertising for some product sent to a mailing list or newsgroup.

Today a cloud based anti spam service is one of the simplest and most manageable ways of eliminating the unwanted and unsafe emails that standard email filters fail to detect. As with most SaaS (software as a service) products, a cloud based anti spam service has no capital expense and minimal maintenance overheads.

Services for cloud based spam filtering work using multi-layered security mechanisms to inspect every inbound email against lists of senders and domains known to be sources of spam. They also check for breaches of sender policy frameworks to detect phishing and spoofed emails.