Sendmail Sender Verification

[Stephen Swaney]

I had lunch a few weeks ago with the AOL postmaster at a spam conference
here in the states. Based on the luncheon discussion I believe that OMR
stands for Open Mail Relay. I believe that AOL has implemented a mail delay
scheme something like:

1. A message comes in from an "unseen" address
2. The message is queued until AOL runs an Open Mail Relay test (this is
very quick).
3. If the sending system is not an OMR the message is delivered and the OK
system is added to the good senders database.
4. If the sending system is an OMR, the message is rejected with an
appropriate error code and the OMR system is added to the bad senders
database.

I seem to remember that records are expired from both databases after a day
or two.

Steve

Stephen Swaney
President
Fortress Systems Ltd.
Steve.Swaney at FSL.com
 

> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
> Behalf Of Ugo Bellavance
> Sent: Tuesday, March 30, 2004 6:06 AM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: Sendmail Sender Verification
> 
> >-----Message d'origine-----
> >De : Mike Kercher [mailto:mike at CAMAROSS.NET]
> >Envoyé : 30 mars, 2004 01:28
> >À : MAILSCANNER at JISCMAIL.AC.UK
> >Objet : OT: Sendmail Sender Verification
> >
> >
> >I've been noticing more and more log entries from aol.com
> >lately similar to
> >the following:
> >
> >Mar 29 22:18:24 avwall sendmail[29603]: i2U4INJU029603:
> >from=<>, size=3001,
> >class=0, nrcpts=1, msgid=<200403300421.XAG19946 at rly-xk01.mx.aol.com>,
> >proto=ESMTP, daemon=MTA, relay=omr-m11.mx.aol.com [64.12.138.23]
> >Mar 29 22:18:30 avwall sendmail[29620]: i2U4INJU029603:
> >to=<username at somedomain.com>, delay=00:00:07, xdelay=00:00:00,
> >mailer=local,
> >pri=123001, dsn=2.0.0, stat=Sent
> >
> >I assume that the omr- stands for Open Mail Relay or something
> >of the sort
> >and I also assume that it is verifying that the email address
> >is deliverable
> >prior to delivering an email from an address to the final AOL
> >recipient.  I
> >suspect they are doing something like this to combat their massive spam
> >flow.
> 
> http://postmaster.aol.com/info/servers.html
> 
> OMR : outbound mail relay.
> 
> Are you an aol subscriber?
> 
> Was that an inbound or outbound message?
> 
> >
> >Has anyone implemented anything like this with sendmail.  I
> >know it would
> >introduce additional network traffic, but might it be worth
> >the trade-off?
> >Thoughts?
> >
> >Mike
> >
> 
> --
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
> 
> Fortress Systems Ltd.
> www.fsl.com
> 



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