On Thu, Nov 20, 2014 at 6:39 AM, Bernd Wurst <be...@bwurst.org> wrote:
>
>
> I don't say that this rule is bullshit or it must be changed. I just
> wonder why most of the folks out there managed to handle it the other
> way and courier does not.
>
I think you're wrong about your "most of the folks out there".
If you substitute "the minority" for "most", perhaps you'd be right.
When a DNS server presents records in direct violation of the standards,
this does result in problems.
This is not a Courier-specific problem.
>> My current example is mail from the Domain "isoloc.com":
> >> isoloc.com. 600 IN MX 10 217.160.79.52.
> >> isoloc.com. 600 IN MX 10 smtp.isoloc.com.
> > there is no TLD named 52. in fact, the MX points to nonexistent host
> > "217.160.79.52." (see the trailing dot?).
>
> It's kind of easy to check if it is an IP address if there is no such
> TLD.
This is akin to a spelling mistake.
The MTA should not have to check for spelling mistakes.
> And additionally: courier could be tolerant if there is one valid and
> one invalid MX.
>
I think this is your ONLY valid point in your argumentation.
I like courier to be standards compliant in many ways. But times change
> and now, we operate one of a really small amount of mail servers that
> cannot handle this invalid domain. Other can do. So from the sender's
> perspective, we are the evil ones not to accept their mail.
>
Don't accept blame for others' errors.
You need to explain to the sender something like this:
"Your provider has a configuration error that makes it difficult to
reliably deliver e-mail to others.
Occasionally, this configuration error will result in a failed delivery. At
other times, the message may get through.
Your e-mail delivery will become more reliable if your vendor corrects
their DNS records."
Chances are very good, you see, that this sender sees deliverability
problems often, not just in sending e-mail, but in receiving it.
The bonus with fixing this invalid DNS entry is that it fixes the problem
for other MTAs, and you don't have to wait for someone to finish arguing
against you on a mailing list before maybe accepting a patch that you write.
--
Jan
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