New York—Email marketing campaigns are plagued by a lack of response and not much adjustment by marketers to solve the problem, according to a new study from deliverability company Return Path.

The new study—“The One-Way Conversation: Email Marketing to the Non-Responsive Subscriber”—analyzed the continuing email efforts of 40 e-commerce companies after Return Path purchased a single product from each. A majority of the studied marketers sent follow-up emails at a steady, high frequency for a 19-month period despite a total lack of response—no opens, clicks or other purchases.

Eventually, 27% of the companies stopped sending email, but a quarter stopped without any attempt to re-engage or request continuing opt-ins.

“We strongly recommend that email marketers monitor their subscriber responses ... and adapt their campaigns to either slow down the emails to once per month or send a repermission email to determine subscribers’ continued interest in receiving emails,” said Stephanie Colleton, director-professional services at Return Path.