1.1 --- a/thesis/tex/5-Improvements.tex	Wed Jan 28 16:49:45 2009 +0100
     1.2 +++ b/thesis/tex/5-Improvements.tex	Fri Jan 30 21:20:00 2009 +0100
     1.3 @@ -282,7 +282,7 @@
     1.4  The two approaches for spam handling were already presented to the reader in section \ref{sec:functional-requirements} as \RF\,8 and \RF\,9. Here they are described in more detail:
     1.5  
     1.6  \begin{enumerate}
     1.7 -\item Refusing spam during the \SMTP\ dialog. This is the way it was meant by the designers of the \SMTP\ protocol. They thought checking the sender and recipient mail addresses would be enough, but as they are forgeable it is not. More and more complex checks need to be done. Checking needs time, but \SMTP\ dialogs time out if it takes too long. Thus only limited time during the \SMTP\ dialog can be used for checking if a message seems to be spam. The advantage is that bad messages can simply get refused---no responsibility for the message is taken and no further system load is added. See \RFC2505 (especially section 1.5) for detail.
     1.8 +\item Refusing spam during the \SMTP\ dialog. This is the way it was meant by the designers of the \SMTP\ protocol. They thought checking the sender and recipient mail addresses would be enough, but as they are forgeable it is not. More and more complex checks need to be done. Checking needs time, but \SMTP\ dialogs time out if it takes too long. Thus only limited time during the \SMTP\ dialog can be used for checking if a message seems to be spam. The advantage is that bad messages can simply get refused---no responsibility for the message is taken and no further system load is added. See \RFC\,2505 (especially section 1.5) for detail.
     1.9  
    1.10  \item Checking for spam after the mail was accepted and queued. Here more processing time can be invested, thus more detailed checks can be done. But, as responsibility for messages was taken by accepting them, it is no choice to simply delete spam mail. Checks for spam do not lead to sure results, they just indicate the possibility the message is unwanted mail. \person{Eisentraut} indicates actions to take after a message is recognized as probably spam \cite[pages 18--20]{eisentraut05}. The only acceptable one, for mail the \MTA\ is responsible for, is adding further or rewriting existing header lines. Thus all further work on the message is the same as for non-spam messages.
    1.11  \end{enumerate}