Many people receive unsolicited emails known as spam. In some cases, the sending address used for spam is forged or "spoofed," in order to look legitimate and bypass the spam filter.
You can protect yourself by creating an SPF record for your domains. This confirms that the actual owner of the email account sent the mail, and will make it easier for email providers to identify spammers that are trying to impersonate you by using spoofing.
SPF does not prevent the sending of spam. But with SPF you indicate which servers are authorized to send emails for your domain. This way, mail systems all over the world recognize whether an email is coming from you when it is received. E-mails that falsify your sender can then be rejected or marked as spam.
To learn more, visit the article on Using an SPF Record to Prevent Spam.