More marketers selected email as their most important marketing channel this year than any other channel, according to a survey by Experian QAS. However the survey also found that many marketers have to contend with inaccurate or duplicate customer data that can hamstring email marketing efforts. 94% of respondents suspect their customer information may be inaccurate. On average they believe 17% of their data may be bad. 29% report losing a customer because of inaccurate information.