Spam has grown into a massive problem – not just at UW but nation-wide. Studies estimate that spam represents between 40 and 60 percent of all email. The spam problem is a difficult one to solve. Although spam filtering software is well developed, even the most sophisticated software occasionally misreads some legitimate messages, treating them like spam. Techniques used by spammers to evade spam filtering software are constantly evolving, as are the rules used to detect the spam. Users can expect to see some ebb and flow in the proportion of spam that is identified by filtering as spammers try new approaches, followed by updates to the filtering software to address those approaches.