Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!exodus!red-dwarf!pallas From: pallas@eng.sun.com (Joseph Pallas) Newsgroups: comp.mail.sendmail Subject: Re: Sendmail host canonicalization broken? Message-ID: Date: 15 Apr 91 21:48:28 GMT References: <3006@weber.sw.mcc.com> <1991Apr12.235346.28444@mp.cs.niu.edu> <12665@pt.cs.cmu.edu> <1991Apr14.002726.9334@mp.cs.niu.edu> Sender: news@exodus.Eng.Sun.COM Lines: 34 In <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. RFC1123 says this (5.2.18): o Some systems over-qualify domain names by adding a trailing dot to some or all domain names in addresses or message-ids. This violates RFC-822 syntax. and this (6.1.4.3): (a) There MUST be some convention for denoting that a name is already complete, so that the abbreviation method(s) are suppressed. A trailing dot is the usual method. How is this possible? Easy. Section 5.2.18 is talking about SMTP, while Section 6.1.4.3 is talking about user interface. In 5.2.18 we are told that ONLY fully qualified domain names may be used in SMTP by an Internet host, so there is clearly no need to distinguish names that are not fully qualified. Conclusion: If you accept mail addresses with host names that are not fully qualified, then you had better turn them into fully qualified names before passing them on. And if you do accept abbreviations, you'd better provide a convention for overriding them. So, in our hypothetical example, the user can send mail to "user@eiffel.fr" or to "user@eiffel.fr.", and the mail will go to (822-address) "user@eiffel.fr.mcc.com" or to (822-address) "user@eiffel.fr", as appropriate. joe