Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!cheops.cis.ohio-state.edu!karl From: karl@cheops.cis.ohio-state.edu (Karl Kleinpaste) Newsgroups: comp.mail.sendmail Subject: Re: How to recognize domain literals Message-ID: Date: 2 Dec 89 20:08:12 GMT References: <8911292029.AA13662@jvncf.csc.org> <1436@utkcs2.cs.utk.edu> <3472@jhunix.HCF.JHU.EDU> <1439@utkcs2.cs.utk.edu> Sender: news@tut.cis.ohio-state.edu Organization: OSU Lines: 18 In-reply-to: moore@betelgeuse.cs.utk.edu's message of 2 Dec 89 06:39:47 GMT It seems to me that you can't expect the MX'd addresses to be the same, because although you may want to be able to send mail to a host via its IP address, the reason for the MX record's existence is that the host in question doesn't run a mailer in the first place; knowledge of the IP address is useless. Ultimately, if one is trying in desperation to get in touch with a postmaster or sysadmin, one can always use "whois" to find out who the responsible people are, or alternatively, "telnet 11.22.33.44 smtp," and do it The Hard Way. This is useful in any event, for the more creative applications of VERB and VRFY, not to mention verification of worm immunity. User interface usage of email to IP addresses is strictly passe'. Real postmasters send mail via telnet to the SMTP port, --karl