Re: another DNS problem

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On Sun, 2010-10-31 at 02:16 +0400, Hiisi Troll wrote:
> In the provided sendmail.mc file there's an option:
> define(`SMART_HOST', `smtp.direct.ru')dnl
> I thought it relays all my outgoing mail to ISP smtp server. Or am I
> wrong here?

The smart host would be the name of the ISP's mail server.  If that's
correct, then you should be able to send mail via your own SMTP server,
to the ISP's SMTP server, then out to the real world.  Just the same as
if you'd emailed directly through the ISP's SMTP server.

However, you will need to be sending *from* an address that's real to
the outside world.  i.e. One that anyone in the world would be able to
write to, and you receive it.  In as much as the domain name has to be
real, and have a public IP.  Either, because you wrote the message with
such a "from address," or your SMTP server masquerades all outgoing mail
with such a domain name in the from address.

Those are the basics, further restrictions may apply depending on how
other parties do their anti-spam protections.

If I were to try to post to one of your samples, root@xxxxxxxx my system
(or another's) would be trying to work out the following:

Find the MX record for kello.ru

 dig kello.ru MX
 ;; ANSWER SECTION:
 kello.ru.		86400	IN	MX	10 mail.kello.ru.

So far, so good.  Now, we'll have to find the IP address for
mail.kello.ru, to make a connection.

 dig mail.kello.ru
 ;; ANSWER SECTION:
 mail.kello.ru.		86307	IN	A	212.16.23.132

Now, if that's the correct IP address, then DNS records for your tests
should be all fine, and it's another problem that needs resolving.  The
very basics of email check out.

Here's just one thing that might be a problem:  Let's try finding the
domain name for that IP, as a reverse look-up, as is typically done by
various mail servers as part being careful.

 dig -x 212.16.23.132

And there is no answer.  None at all, not even a different domain name
(as is commonly the case, when you share IPs with other people).  In
some cases, because that's a check that many others will do, it will
mean "no mail for you!"  This can be a problem for, both, incoming and
outgoing mail.

And if you'd Google searched "451 DNS temporary failure" as in your
first posting's error message:

  "stat=Deferred: 451 DNS temporary failure"

You would have found this about two down from the top returned pages:

  "SMTP Service Info
  23 Feb 2004 ... 451 Bad reverse DNS: This is a temporary failure  
  indicating that you are attempting to connect from a host that does
  not have reverse DNS. ...

If you cannot set your own reverse DNS, you'll have to ask your ISP (or
mail host) to set it for you.  If they cannot, you're stuck.

Another problem with trying to send or receive mail from the outside
world will depend upon what numerical IPs you have.  If it's within the
range of addresses handed out by an ISP to their clients, particularly a
dynamic address, though still applicable to static address customers,
then many other people will not be able to post to you, because their
SMTP servers will refuse to make direct connections to customer IPs.

Then there's plain old internet racism - you have a .ru top level domain
name in your address.  Some will blackban that, just for the sake of it.
Though, if you're doing local tests, I kind of doubt that other nearby
neighbours would be doing that sort of banning.

-- 
[tim@localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.



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