Autor: Willie Viljoen Data: Para: Greg Louis CC: exim-users Assunto: Re: [Exim] MX Record points to non-existent host
On Saturday 22 February 2003 15:38, Greg Louis wrote: > This is one aspect of a problem that has plagued me for years. My
> employer manufactures and sells stuff. My users want to be able to
> receive email from, and successfully send email to, our business
> partners and our customers, no matter how ignorant and/or stupid their
> IT people might be (many small firms can't afford real IT people in the
> first place, and some engineer or salesman looks after the servers in
> his very limited spare time). It's not an unreasonable desire.
I disagree.
Remember, simply because you have adapted your MTA to tolerate this, other
people's MTA just might not. Infact, most experienced administrators will
enforce the rules strictly. While it may seem unreasonable to force
everybody to follow the same rules, I think it's alot more unrealistic a
demand to want everybody to lower their standards and "bend the rules" to
accomodate one company's misconfigured server.
Simply adapting your server to be liberal with your customers' servers might
make you seem to be flexible, which is always a good thing, but it
certainly won't fix their problem in the larger scheme of things. Most
administrators are not flexible, infact, most of them can be very
draconian, some will even add slightly misconfigured domains to a local
blacklist, just for being misconfigured.
This is not an exagiration, a set of public blacklists exist at
rfc-ignorant.org, which are used as a shared source of information
regarding misconfigured servers and domains, which are blatantly blocked by
all users of the lists. This means that if your customers are trying to do
business with somebody who uses such a list, they might well find
themselves being treated in the same way that most companies treat
spammers, simply because they didn't take the time to configure their
server properly.
The RFCs that deal with how mail is dilvered over the internet are public
documents, freely available to anyone who wished to read them. The
requirements in these documents are not unreasonable, and internet mail has
been working perfectly for many years with these requirements in place.
> I hacked smail3, when I was using that, to disable a lot of verification.
> Now that I've switched to exim 4, I'm still finding out about, and
> turning on, stuff like helo_accept_junk_hosts and helo_allow_chars, to
> cope with messed-up and misnamed exchange servers and so forth. It
> would be nice to get the customers to fix their messes, but it's not
> good for business to tell customers they've cocked up.
Actually, it is. We find that sending their IT person/people a nice e-mail
(or a fax, if no e-mail is getting through at all) explaining to them what
the problem is, and citing reasons for the regulation from an authoritative
document like an RFC or an Internet Draft will always get their attention.
I even offer to come and help them fix the problem, at a price, ofcourse.
Here and there, the odd sales manager turned IT person will feel insulted
that you should question his skills, but this kind of person will cause
problems regardless of wether you try to help him onto the straight and
narrow or not.
The general perception, however, from customers, is that you know what you
are doing, and are watching their back, so to speak, most customers, and by
this I mean all of them, except the unreasonably stuborn, seem to prefer
this to the indifference showed by most service providers these days.
I wouldn't tell them they've cocked up, they might not appreciate such
candor, but explaining a problem to them in great detail, and offering a
list of solutions with the explanation, or offering to come and fix it
yourself, will generally not offend anybody.
> IMHO it ought to be possible to configure one's MTA to try harder to
> find a way through, even if that involves connecting to an IP address
> that doesn't have a reverse map at all.
You are entitled to your opinion, but the fact of the matter is that MTAs
which allow users to, as it were, get away with anything, just add to the
increasing flagrant disregard for regulations and standards that is causing
most of the serious problems on the internet today.
Unscrupelous commercial developers, who would persue nothing but profits,
create software all the time which fuels the lawlessness, but for those who
value financial gain over integrity, I have no sympathy.
If every MTA had been released with relaying disabled by default (such as
Exim 4 is), there would be no spam problem on the internet.
If every commercial firewall instructed users that they NEED to allow ICMP
types 11, 12, 13 and 14, there would be no fragmented TCP packets, and no
long time-outs and mysterious errors on the internet.
Problems should be solved, not managed.
--
Willie Viljoen
Freelance IT Consultant
214 Paul Kruger Avenue, Universitas
Bloemfontein
9321
South Africa
