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Re: Re: step by step deploment

2004-01-21 23:28:35
In <DDB1E4CC-4C9B-11D8-ABBC-003065A75E32(_at_)lammy(_dot_)net> ty lammy 
<ty(_at_)lammy(_dot_)net> writes:

Yes, and I see a lot of invalid HELO strings.  (Ok, the RFC says the
HELO string is just a comment, but...)

So, the problem is, these systems will be able to send SPF-enabled
email just fine, but any bounces created by them will be rejected.
That doesn't strike me as a good thing to have happen.

To which RFC are you referring?  If it's RFC 2821 it says exactly the
opposite:

Yeah, you are right, I was speaking too loosely about the HELO
string.

You quoted RFC2822 section 3.6, but this section adds some more info:

4.1.1.1  Extended HELLO (EHLO) or HELLO (HELO)

   These commands are used to identify the SMTP client to the SMTP
   server.  The argument field contains the fully-qualified domain name
   of the SMTP client if one is available.  In situations in which the
   SMTP client system does not have a meaningful domain name (e.g., when
   its address is dynamically allocated and no reverse mapping record is
   available), the client SHOULD send an address literal (see section
   4.1.3), optionally followed by information that will help to identify
   the client system.  [...]

So, if a FQDN isn't available, the client only SHOULD provide an IP
address on the HELO command.

To the best of my knowledge, the only place the HELO string is
officially used is in the received: headers as "trace information".
Somehow I seem to recall something that said that an SMTP server isn't
supposed to reject based on the HELO string, but I can't find that and
I could easily be remembering things wrong.


So, yeah, the HELO string isn't a comment, but you can put just about
anything in it and get by pretty well.  :-<


-wayne

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