(this must be my week for past-sins pennance related to RBL's.) today someone whose e-mail was blocked when they tried to send it to an at&t customer, asked the authors of RFC 2317 to please unblock their address. as the only such author whose e-mail address hasn't changed since RFC publication i pretty much assumed that the other two guys weren't hearing this, and so i investigated. the complainer showed me this text: <foo@att.net>: host gateway2.att.net[12.102.240.23] said: 550-24.248.126.43 blocked by ldap:ou=rblmx,dc=worldnet,dc=att,dc=net 550 Blocked for abuse. See http://www.att.net/general-info/rblinquiry.html" (in reply to MAIL FROM command) i looked at the URL thus indicated, and the link for Information for end-users whose messages have been blocked. is http://www.att.net/general-info/mail_info/block_enduser.html which says: What to do: Ask your system administrator to submit identifying information to the DNS. For more information, your administrator should refer to http://www.faqs.org/rfcs/rfc2317.html In the meantime, you should use a fully registered domain for sending your messages, such as the mail system from an ISP or one of the major free e-mail services. now, i count myself as a master of the obscure reference, but this is over the top. can someone from at&t worldnet please contact me for the purpose of explaining what RFC 2317 could possibly have to do with spam complaints? (and btw, if you're going to block inbound e-mail, you need to give senders some idea of how to get unblocked. not for fairness, just for practicality. and this parenthesized paragraph is why i count this screed as not-off-topic.)