If your mail servers are encountering persistent deferrals (i.e., 4xx SMTP error messages in your logs) when connecting to Yahoo! Mail servers, this may indicate that we are seeing unusual traffic or are getting considerable complaints regarding emails coming from your servers. We encourage you to examine your outbound mail queues to ensure that unsolicited emails are not being sent by any users or compromised machines within your network.

If your outbound mail queues do not show any signs of abusive activity, please fill out this form so we may investigate the persistent deferrals your servers are experiencing.