AIX Tip of the Week

Subject: Potential Spam Relay Issue with Default AIX sendmail Configuration

Audience: All

Date: August 29, 2005

If you are using AIX sendmail, you should consider the following fix to prevent spammers from using it as an open mail relay.

The exposure applies to AIX 5.3 ML1 and earlier distributions. The exposure was resolved in AIX 5.3 ML2. For more information, see

Name: CAN-2003-0285 (under review)

Description: IBM AIX 5.2 and earlier distributes Sendmail with a configuration file ( with the

(1) promiscuous_relay, (2) accept_unresolvable_domains, and (3) accept_unqualified_senders features enabled

which allows Sendmail to be used as an open mail relay for sending spam e-mail.

Bruce Spencer,

August 29, 2005