Spam is unsolicited mass-mailed email, usually containing an advertisement. Spammers send their messages to large numbers of addressees, often obtaining those addresses without the permission of the address owner. Spam tyically contains offensive and unwanted material, or even viruses and other malware.
Microsoft Office 365 uses Microsoft Forefront for spam filtering. Users will be notified every three days if messages are quarantined and, by following their email instructions sent by Microsoft, will be able to view these messages.