This article was posted to the Usenet group alt.hackers in
1995; any technical information is probably outdated.
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Re: Mail systems on AOL
Article: 8407 of alt.hackers From: spc@news.gate.net (Sean 'Captain Napalm' Conner) Newsgroups: alt.hackers Subject: Re: Mail systems on AOL Date: 7 Aug 1995 22:24:23 -0400 Organization: Cybergate, Inc. Lines: 65 Approved: not sendmail Message-ID: 406hsn$2a4i@hopi.gate.net NNTP-Posting-Host: spc@hopi.gate.net NNTP-Posting-User: spc Status: RO
In article <405vfu$krm@senator-bedfellow.MIT.EDU> dedeo@mit.edu (Simon Joseph Dedeo) writes: >Having read the RFC's for SMTP, I've been led >to believe that sending mail is impossible unless >one can telnet to the SMTP port of the destination >site (usu. 25). How, then, does mail from aol.com >"escape"? Mail *seems* to be coming from something >like "emout04.mail.aol.com", but I'm unable to telnet >to port 25 there. What's up with that? Isn't the >ability to access that port necessary for two >machines to exchange message texts? > >And now I'm *really* getting out of my league... >When mail is addressed "jloser@aol.com", the mail >program must access the DNS to locate the address >to telnet to, right? So why does a telnet to aol.com >return a "No address associated with name" error? > The mail transport agent doesn't just telnet to port 25 of the address portion of the email address. Well, it does, but only if it can't find a certain type of DNS record for the address portion. For instance, for AOL: [spc]hopi:/u3/spc>nslookup Default Server: odin.gate.net Address: 199.227.0.2 > set type=mx > aol.com Server: odin.gate.net Address: 199.227.0.2 Non-authoritative answer: aol.com preference = 15, mail exchanger = mail05.mail.aol.com aol.com preference = 15, mail exchanger = emin04.mail.aol.com aol.com preference = 15, mail exchanger = emin05.mail.aol.com aol.com preference = 15, mail exchanger = mail03.mail.aol.com aol.com preference = 15, mail exchanger = emin06.mail.aol.com Authoritative answers can be found from: aol.COM nameserver = HP81.PROD.AOL.NET aol.COM nameserver = OPS01.OPS.AOL.COM aol.COM nameserver = NIS.ANS.NET aol.COM nameserver = NS.ANS.NET mail05.mail.aol.com inet address = 152.163.172.109 emin04.mail.aol.com inet address = 198.81.10.11 emin05.mail.aol.com inet address = 198.81.10.36 mail03.mail.aol.com inet address = 152.163.172.49 emin06.mail.aol.com inet address = 198.81.10.44 HP81.PROD.AOL.NET inet address = 192.203.190.18 OPS01.OPS.AOL.COM inet address = 152.163.80.11 NIS.ANS.NET inet address = 147.225.1.2 NS.ANS.NET inet address = 192.103.63.100 > ^D [spc]hopi:/u3/spc> I leave how this exactly works as an exercise to the reader. Also, note that AOL does NOT like this information getting out, as it it's proprietary or something. You have been warned. ObSendmailHack: Actually configuring sendmail.cf so that it only sends the domain name of the network (I did this on) and accept mail sent only to the domain. -spc (Why yes, I can read line noise ... )
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