Q. Can TCPware be configured to disable unauthorized mail relaying and SPAM, and how can I tell if my system allows unauthorized mail relaying?
A. Yes. You can configure the TCPWARE:SMTP_SERVER_REJECT. file to accomplish this. The following is an example SMTP_SERVER_REJECT. file that can be used as a starting point to create your own reject file. In the example, only mail that is from the 10.0.0, the 10.115.140, or the 10.115.141 subnets with a from address ending in flowers.com will be relayed. You can test to see if your system allows relaying of unauthorized messages by telneting to MAIL-ABUSE.ORG from the machine you are testing.
! ! This is a sample reject file for the company FLOWERS.COM. ! ! This file is processed sequentially. In other words, processing ends ! on the first rule that the message applies to. So if you have a ! wildcard accept at the top of this file, then no other rules will be ! processed. ! ! Entries can have one of the following formats: ! ! from_user [from_ip to_user action action-data] ! ! :rfc822 header ! ! Wildcards can be used in FROM_USER, FROM_IP, and TO_USER. ACTION is ! the reject action, which is one of: ! ! n Don't reject, but rewrite TO address to be ACTION-DATA. ! If ACTION-DATA is blank then we simply deliver to ! TO_USER. ! ! y Reject and use optional ACTION-FIELD as a rejection ! message format that can contain up to three %s ! formatting designators for mail from, mail to, and ! local domainname. ! ! q Reject quietly -- don't inform Sending SMTP Client that ! message will be discarded. If only FROM_USER is specified ! other fields default to FROM_IP=*, TO_USER=*, and ACTION=n. ! ! Don't rewrite or reject any mail to "postmaster*" ! * * postmaster* n ! ! ! Accept all messages with MAIL FROM:<> (bounce messages) ! This rule is commented out because you probably don't want it, ! although we're _supposed_ to always accept it. This is the main ! method relay attacks use, by always saying they are from <> to take ! advantage of that RFC hole. ! ! <> * * n ! ! Reject anything with a Message-ID that appears to have originated from ! cyberpromo.com or nowhere.com ! :Message-ID: <*@cyberpromo.com> :Message-ID: <*@nowhere.com> ! ! Reject mail from well-known SPAM sites with sample non-standard error ! messages. ! <*answerme.com> * * y "Spam from <%s> rejected" <*cyberpromo.com> * * y "Spam from <%s> to <%s> rejected" <*pleaseread.com> * * y "Spam rejected;%.0s%.0s Contact postmaster@%s" ! ! Disallow percent-hacks (e.g, joe%somewhere.com@flowers.com) ! * * *@*@*flowers.com y "No forwarding-path relaying allowed" ! ! Disallow "!" UUCP hacks (e.g. somewhere.com!joe@flowers.com) ! * * *!* y "No UUCP relaying allowed" ! ! Rewrite all mail to webmaster to the postmaster. ! * * webmaster@*flowers.com n postmaster@flowers.com ! ! ! Disallow relaying through our mailer, and only allow users on our ! networks to claim to be from our company (flowers.com) ! * * *@flowers.com n * * *@daisy.flowers.com n * * *@[10.0.0.1] n ! <*flowers.com> 10.0.0.* * n <*flowers.com> 10.115.140.* * n <*flowers.com> 10.115.141.* * n ! ! Allow our internal systems to bounce mail out. !