Re: [Exim] Exim 4.02 new "feature"

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Autor: Jeff Mcadams
Data:  
Para: dana_booth
CC: exim-users
Asunto: Re: [Exim] Exim 4.02 new "feature"
Also sprach dana_booth
>However... In this particular instance, (the implementation of MTA
>software) Microsoft is still in the minority. I'm begging you guys,
>please don't start allowing underscores or other illegal host/domain
>name characters just because you have a reject log full of Microsoft
>hits. There must be a way to make this more public; to force those who
>"administer" Microsoft software to come into compliance.



I have mixed feelings...practically speaking, as a business, rejecting
underscores (in particular) is a sure recipe for business suicide for an
ISP.

On another hand, I firmly support standards compliance...as such, I
would support Phillip in making the default to be compliant with the
RFC's (not allowing underscores, for example), and this is what he has
done.

On yet another hand, though (three hands?), standards are all about
supporting interoperability. Thus the "Be liberal in what you accept,
and conservative in what you send" concept. Allowing underscores
enhances interoperability in almost all cases, and given that the HELO
hostname is really (practically) not used for anything, then accepting
underscores really does no practical harm.

I also look at this situation and consider that 2821 is pointing to a
section of an RFC about DNS as the rational for this restriction.  Given
that, I think it would be wise to fix DNS servers (particularly BIND as
its the 800 lb. gorilla in that category) to not allow underscores by
default (which I don't *think* is the case at this point, but would be
happy to be shown to be wrong on this point).  Once the DNS system
enforces the no underscores concept in a more widespread fashion, then
it will be much more reasonable/practical to reject mail based on having
underscores in the HELO name.
--
Jeff McAdams                            Email: jeffm@???
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456