[exim-dev] [Bug 485] Exim mistakenly prohibits underscore (_…

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Συντάκτης: bug485
Ημερομηνία:  
Προς: exim-dev
Αντικείμενο: [exim-dev] [Bug 485] Exim mistakenly prohibits underscore (_) in /HELO/EHLO commands
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http://www.exim.org/bugzilla/show_bug.cgi?id=485





------- Comment #4 from bugzilla.exim.org@??? 2007-03-18 05:24 -------
graeme@??? wrote:

>
> RFC1425 obsoleted by 1651, then by 1869, then by 2821. From RFC2821:
>
> The argument field contains the fully-qualified domain name of the SMTP
> client if one is available.
>
> An FQDN may not contain underscores, as per the RFCs for domain name
> construction (I forget which).
>
> If you have a problem, set one or more of:
>
> helo_allow_chars = _
> helo_accept_junk_hosts = some.host.name:some.ip.add.ress
>
> All of which are well documented.


Yes, I ended up setting the helo_allow_chars. Since the newer RFC's
don't really provide explicit syntax definitions, I went by the older
ones which do. I also don't have 'verify = helo' enabled, which I would
expect to have rejected the HELO response.

It's not a huge deal either way. I have it working now. I should point
out that to really enforce strict FQDN syntax, the first character of a
label can only be a letter and the last can only be a letter or digit.
The first character cannot be a digit or hyphen, nor can the last be a
hyphen. 3com.com is not a syntactically correct FQDN and should be
rejected as such ;-) RFC 1035 Section 2.3.1

-David

>
> Graeme
>


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