WP DB Backup is the premier database backup plugin for Wordpress. Simply install the plugin and then enter the email address you want the backups sent to.
Choose the backup frequency based on your blogs activity. I backup once per day, because I receive a moderate amount of comments. If you receive a greater number of comments throughout the day, or simply post more frequently, then increasing the backup frequency to twice per day is probably a good time.
Click here to read more about email backups.
