Complaints sent directly to us through our abuse address are forwarded by postmasters at companies like AOL and Yahoo. Email providers monitor the amount of complaints closely as they can indicate unsolicited emails or poor list maintenance practices, often leading to blocks or delays. This can have a serious impact on our ability to deliver mail for our other clients.
Due to the risk this poses we must require our users keep these complaint rates below 0.3%.
ISPs have set thresholds for complaints, unsubscribes, and abuse complaints that email service providers (ESPs), such as VerticalResponse, are required to enforce. If these thresholds are exceeded, it could prompt your account to be blocked from mailing.