Mail Scanner Service (or MS) is a replacement for Spamassasin, now removed from your control panel.
Since emailed spam has become such a huge problem, we've undertaken to install Mailscanner services, which acts like an additional filter to catch junk and viruses (with the addition of a real-time antivirus scanner) before they hit your inbox. To access your settings, just log into your control panel (www.domain.com/cpanel/) and on the first page look for the icon in the lower right for "MailScanner Configuration"
After clicking that, you should then see the main settings panel for Mailscanner, shown here:
Each domain on your account can have separate settings, such as what to do with low or high scoring spam, what those numbers are to represent low and high (See "other settings" below), as well as shutting of spam checking completely. By default, low scoring spam is sent to your mailbox, but the subject will be rewritten slightly to show you what it was rated as. High scoring spam (the ones that are most definitely spam) are currently being deleted. Feel free to change this to whatever you like.
At the top of the mailscanner confguration page are two addition links: "Email Black/Whitelist settings" and "Other Settings".
The Black / Whitelist is for addresses or domains that you wish to pass right through no matter what the score, or reject no matter what. Whitelist to keep and not filter, blacklist to reject at all times. Use this sparingly.
Lastly is the Mailscanner numerical score settings (select "other settings" on the main MS page). Using this, you can tell MS what levels should be considered low or high scoring spam, as well as list an additional email address to send messages marked as spam to, in case you want to check for false positives.