Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!mp.cs.niu.edu!rickert From: rickert@mp.cs.niu.edu (Neil Rickert) Newsgroups: comp.mail.sendmail Subject: Re: Sendmail host canonicalization broken? Message-ID: <1991Apr15.222245.6789@mp.cs.niu.edu> Date: 15 Apr 91 22:22:45 GMT References: <12665@pt.cs.cmu.edu> <1991Apr14.002726.9334@mp.cs.niu.edu> <1991Apr15.200923.11004@csl.dl.nec.com> Organization: Northern Illinois University Lines: 38 In article <1991Apr15.200923.11004@csl.dl.nec.com> ylee@csl.dl.nec.com (Ying-Da Lee) writes: > >In article <1991Apr14.002726.9334@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes: >> >> RFC1123 specifically warns that addresses with a final period are INVALID. > >Furthermore, RFC 1123 (I assume it's the last item of section 5.2.18 >that Neil is refering to) does not automatically comes into play here. >It states > Some systems over-qulaify domain names by adding a trailing > dot to some or all domain names in addresses or message-ids. > This violates RFC-822 syntax. > >It would be a clear violation of RFC-822's syntax if a mailer >used user@eiffel.fr. as the recipient address on the envelop. But this is exactly the point. If you allow 'eiffel.fr' to mean that it should be qualified in the local domain, but 'eiffel.fr.' to mean it should not, then consider what happens: A user on your system sends mail to 'user@eiffel.fr.' with the final period meaning it should not be qualified locally. Your mailer removes the final period on the envelope address, as you stated. It is relayed to 'host.other.domain'. Since there is no longer a final period, if this relay host follows your philosophy it will attempt to qualify 'eiffel.fr' in its own local domain. Worse still, because of the possible use of MX records, you can never know where you are relaying mail. The reliable approach is to NEVER allow addresses such as 'eiffel.fr' to be locally qualified. -- =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*= Neil W. Rickert, Computer Science Northern Illinois Univ. DeKalb, IL 60115 +1-815-753-6940