There are several common ways that spammers can get your email address:

• Crawling the web for the @ sign. Spammers and cybercriminals use sophisticated tools to scan the web and harvest email addresses. If you publicly post your email address online, a spammer will find it.
• Making good guesses... and lots of them. Cybercriminals use tools to generate common user names and pair them with common domains. These tools are similar to the ones that are used to crack passwords. And they work.
• Tricking your friends. Even if you know better than to publicly post your email address on the web, it could still be stored in the email inbox of anyone who's ever emailed you or whom you've ever emailed. Cybercriminals can steal contact lists or use social engineering to trick people into giving them access.
• Buying lists. Spammers can purchase lists legally and illegally. When you sign up for a website or a service, make sure you read the privacy policy carefully to find out what the site plans to do with your email address.

It pays to keep your email address as private as possible, but sometimes it seems like there's nothing you can do to keep it out of the hands of spammers. For this reason you have to combine smart privacy practices with strong email filters.

All of the most recent versions of Microsoft's email services (including Hotmail) use a strong filter called SmartScreen. For more information, see Help keep spam out of your inbox.