Voluntary email lists may not be reaching consumers as much as marketers would like. A Lyris Technologies study found that anywhere from one to 20 percent of permission-based emails from reputable organizations are blocked or filtered as spam.

Lyris deliverability experts spent three months monitoring opt-in email lists of top universities, professional sports teams, high-profile non-profits and major television networks.

“Even after obtaining a recipient’s permission to email, there are still a number of steps marketers can take to ensure maximum delivery of their campaigns,” says Dave Dabbah, marketing director of Lyris Technologies.

Lyris recently published a guide titled, “The Opt-In Marketer’s Checklist for Inbox Delivery,” designed to help marketers ensure delivery of voluntary email marketing campaigns.

“Email is still unrivaled among online direct marketing channels, but the ever-changing ISP filtering policies can sometimes affect results without businesses even realizing it,” says Dabbah. “This guide is designed to help busy marketers maximize inbox delivery of their messages and realize the full potential of this incredibly powerful medium.”

Dabbah added, “Many marketers are surprised by how much even small adjustments can impact overall performance.”