Despite minor improvements, about 1-in-5 commercial, permissioned emails still fail to reach consumers’ inboxes, according to new research from email and reputation management firm Return Path.

In the second half of 2009, 19.9% such emails never reached consumer inboxes in the United States and Canada — representing only a slight improvement over the first half of the year when 20.7% such emails missed their target.

By contrast, European inbox placement rates fared markedly better with just 15% of requested, permissioned emails never reaching consumer inboxes.