From: Duane Hill (d.hillyournetplus.com)
Date: Wed May 30 2007 - 06:10:46 CDT

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On Wed, 30 May 2007, mouss wrote:

> mouss wrote:
>> Duane Hill wrote:
>>> On Tue, 29 May 2007, mouss wrote:
>>>
>>>> Duane Hill wrote:
>>>>> On Tue, 29 May 2007, mouss wrote:
>>>>>
>>>>>> - if it contains junk characters, then it is invalid both in terms of
>>>>>> the RFC and in terms of common use.
>>>>>> - you can also reject negative numbers: /^-\d+$/. These are invalid and
>>>>>> were never reported in legitimate mail. seems like abroken ratware.
>>>>>> - you can also reject numeric helos: /^\d+$/. They are invalid, and
>>>>>> there doesn't seem to be a lot of legitimate broken sites using these.
>>>>>
>>>>> Doesn't reject_invalid_helo_hostname take care of these invalid helo's?
>>>>> In testing, I can't helo as a negative or positive number with the
>>>>> option. I'm not sure as I can't find the detail of what an
>>>>> invalid_helo_hostname entails.
>>>>
>>>> you may have a reject_non_fqdn_hostname in your config. rejecting "123"
>>>> because it is non fqdn or because it is a numeric helo are different
>>>> decisions. some people cannot reject non fqnd helo's, but they can still
>>>> reject numeric ones.
>>>
>>> I understand that. However, I mentioned reject_invalid_helo_hostname.
>>>
>>>
>>
>>
>> reject_invalid_hostname will reject a helo if it not a valid hostname and
>> not a valid literal IP (IPv4 or IPv6). for "safety|compatibility", postfix
>> will accept a naked IP.
>>
>> Here, a valid hostname is formed with alphanumeric, dots and hyphens. the
>> hostname and all its labels (the strings separated by dots) must start with
>> an alphanumeric. no empty label is allowed (i.e. adjacent dots are not
>> allowed). It must not be all numeric ('1234'). the hostname is limited to
>> 255 chars and its labels are limited to 63 chars.
>>
>> See RFC 1035 for more infos.
>>
>
> I forgot to mention that postfix will accept underscores instead of dashes,
> for compatibility reasons.

All makes sense now. Thanks.

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