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Re: Would your SMTP server accept -> ehlo MAPI1.0 ???

Cross-posted to 3 groups.

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In article <5078AD79.AADEC93F@Man.com>, Mail Man <Mail@Man.com> wrote:

> Recently I've been trying to figure out why a Trendnet TV-IP110w
> IP-camera was not able to connect to my SMTP server to send mail.
> 
> I performed some packet analysis and found that the camera was greeting
> the server with this:
> 
>   ehlo MAPI1.0
> 
> And my server responds with this:
> 
>   501 Invalid domain syntax
> 
> In looking at the ehlo specifications, the greeting is supposed to
> contain something that looks like a domain-name.  So I believe the
> string "MAPI1.0" is being rejected by my server on that basis.
> 
> When I redirect the camera to use my ISP's out-bound MTA server, it
> apparently accepts the ehlo and the email is delivered correctly.  In
> doing so, I see this in the header generated by the camera:
> 
>    X-Status: Alpha
>    X-Mailer: Fitivision Mail API V1.0
> 
> I've updated the camera's firmware, but it doesn't change the ehlo
> string.

Most mail clients often don't have a domain of their own to put in the 
EHLO message. That part of the protocol was designed with the 
expectation that SMTP connections would all be between MTAs. It wasn't 
until many years later that PCs started running mail clients that used 
SMTP to submit mail through a relay.

I checked what Mac Mail does, it sends

EHLO [192.168.3.99]

i.e. the machine's local IP. As you can see, the value of this string is 
nonexistent when the connection is between a mail client and its message 
submission server.

Why do you have your SMTP server configured to check this for local 
clients? It's reasonable to check it for incoming mail from other MTAs, 
as an anti-spam measure, but what are you gaining when you check it on 
authenticated clients?

-- 
Barry Margolin
Arlington, MA

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Would your SMTP server accept -> ehlo MAPI1.0   ??? Mail Man <Mail@Man.com> - 2012-10-12 19:53 -0400
  Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Solbu <solbu@solbu.net.ugyldig> - 2012-10-27 03:31 +0200
    Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-10-27 18:06 +0000
      Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Mail Man <Mail@Man.com> - 2012-10-27 20:14 -0400
        Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Fritz Wuehler <fritz@spamexpire-201210.rodent.frell.theremailer.net> - 2012-10-28 14:07 +0100
          Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Mail Man <Mail@Man.com> - 2012-10-28 12:35 -0400
            Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Anonymous <nobody@remailer.paranoici.org> - 2012-10-28 20:49 +0000
        Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-10-29 22:08 +0000
  Re: Would your SMTP server accept -> ehlo MAPI1.0   ??? Barry Margolin <barmar@alum.mit.edu> - 2012-10-28 22:17 -0400

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