ISPs Block 22 Percent of Permission-Based Email, Believing it to be Spam, Business Wire, 23 Mar 2005

“Twenty-two percent of permission-based email was blocked by the top ISPs during 2004, according to a Return Path study. Corporate email being considered spam by ISPs is a growing problem, up 3.3 percentage points over the second half of 2003. Return Path conducted the deliverability study by monitoring 50,000 marketing and transactional campaigns sent using Return Path's Mailbox Monitor service between January and December 2004. Blocking for each campaign varied from a low of 1 percent to a high of 57 percent.�

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