|| Friends. Messages from people on your friends
list are identified and passed directly to inbox skipping the
remaining spam filtering steps.
|| SPF (Sender Permitted From) determines whether the connecting
machine is allowed to send email for the domain in the 'from' address.
If the domain has not yet set up SPF records a best guess is made to see
if the machine is reasonable.
In the case of a rejected email, the response back to the sender informs
them that the domain has not yet set up SPF records. It also includes how to
register the domain in the 'from' address to allow their emails to be received.
|| Accept Rules. The allow exception rules are then processed,
these are used to bypass normal spam and friends filtering.
Users should be careful setting up such exceptions.
A exception might allow anything with my secret
password in the subject, or from my boss email address.
|| Filters. Next the users filtering and exceptions rules are processed
to check for special rules like, move incoming mail to particular