Microsoft blocks most SPAM that enters the DMACC system, but many still get through. Often email senders are legitimate accounts who had been compromised and their accounts were used to send the messages. They will eventually end up in Microsoft's SPAM filters.
How do we get SPAM messages? This can happen many different ways. Just a few of the common ones are signing up for something online and entering your email address, whether it's a sweepstakes, or even a scholarship offering. Occasionally a friend's email account will become compromised and their address book is harvested.
What can you do? Never respond to SPAM messages. This only validates your email to the sender and gets you added to more SPAM lists. For individual emails, just delete them. If you continually get emails from the same sender, block them. You can do this by right clicking on the email and selecting Junk, then choosing block sender (in Outlook). Also, never open pictures, or click on links in SPAM messages.
If you have fears of your account(s) being compromised, change your password(s). Monitor your accounts for suspicious activity. Monitor your email's Sent items for emails you didn't send and check for Forward or Inbox Rules you didn't create.
If you have questions regarding the legitimacy of an email, you can forward it to firstname.lastname@example.org and we will look into it for you.