E-mail, message unsolicited, SPAM, greylisting, postgrey, postfix filtering

The article summarizes experience obtained during several-year period of anti-SPAM measures having implemented in the network of the University of Ostrava. The article's main focus is in greylisting in Postgrey implementation and Postfix filtering as front-line measures to eliminate SPAM. As demonstrated there is no long- term efficiency decay but efficiency fluctuations are very high so the conclusion about non-existence of long-term decay will have to be reconfirmed in future studies. Also expected orientation of future studies are proposed.

The article summarizes experience obtained during several-year period of anti-SPAM measures having implemented in the network of the University of Ostrava. The article's main focus is in greylisting in Postgrey implementation and Postfix filtering as front-line measures to eliminate SPAM. As demonstrated there is no long- term efficiency decay but efficiency fluctuations are very high so the conclusion about non-existence of long-term decay will have to be reconfirmed in future studies. Also expected orientation of future studies are proposed.