Issue: Mail sent to Yahoo-based addresses, particularly from mailing lists or forms, results in a deferred mail report, as in this example:
SMTP error from remote mail server after initial connection: host b.mx.mail.yahoo.com [126.96.36.199]: 421 4.7.0 [TS02] Messages from (IPADDRESS) temporarily deferred due to user complaints - 188.8.131.52; see http://postmaster.yahoo.com/421-ts02.html
Despite the claims in the deferral message, there are no user complaints regarding either mail from the server or from the domain from which the mail is being sent. A review of the relevant newgroups, operator mailing lists, and spam filtering/blacklists show no complaints regarding mail from the server or from the client domain.
Solution: At this time, there is no solution. Deferred mail will return to the queue for periodic retry, as is the case with other mail that cannot be immediately delivered for any reason. Depending on which of Yahoo's mail servers receives the next connection, the mail may be delivered, or may be deferred once more. This is only controlled by Yahoo, and is not an issue we can address.
Further notes: We, like others, have been unable to receive any answer from Yahoo as to what conditions exist that cause them to defer mail in this manner. Deferrals have occurred on servers where mail activity is minimal at best, and where no automated mailings or forms exist, and on servers where there is high mail traffic, both in- and outbound. When contacted via their form, Yahoo often sends back (days later) a request for information that has already been provided to them, rendering the process useless and unnecessarily time-consuming. The following thread from an operator's group to which we subscribe is an excellent indication of the issues that many people are experiencing at this time with delivery to Yahoo-based mailboxes: http://www.merit.edu/mail.archives/nanog/msg07305.html