New York—Forty-four percent of email opens occur on mobile devices, according to a survey from interactive marketing provider Experian Marketing Services. The report, "Email Market Study: Acquisition and Engagement Tactics," found more than 50% of email marketers responding currently optimize or plan to optimize their emails for mobile viewers. To acquire new subscribers, 78% of marketers use sales associates to collect email addresses; 22% are using pop-up windows on their websites; and 36% still collect email addresses on paper, the survey found. Thirty percent of respondents said they make no fields in a registration form mandatory, suggesting that marketers are focused on acquiring email addresses and using other tactics, such as preference centers and surveys, to gather additional information about customers later, the report found. The study was based on responses from 146 multichannel marketers that are Experian clients conducted via email and online last summer.