Email marketers know that smaller list segments and decreased frequency often lead to higher engagement, but during this year's holiday season many ignored that advice - and saw metrics rise as a result. Best Buy, for example, trimmed its list from 32.6 to 32.3 million, but tripled the number of messages it sent. Inbox placement rose slightly to 97% and open rate nosed upwards as well, from 9.4% to 9.6%.