[Cialug] Hostname issue

[Josh More]

$ dig barracuda.gilstermarylee.com MX

On my system, this shows no DNS entry for barracuda.gilstermarylee.com

The fallback SMTP host (A record) points to 75.149.203.77

A reverse on 75.149.203.77 points to visionitnow.com, which doesn't
match the forward.

As Jonathan points out, a reverse on 66.186.99.236 isn't set up.

There is also no SPF or DOMAINKEYS entry for 66.186.99.236

So, the problem is that the receiving mail server doesn't think you're
a legitimate sender (don't blame it, I wouldn't either).

To fix it:

1) Add an MX record for barracuda.gilstermarylee.com that points to
the barracuda devices's external interface, which is probably
66.186.99.236.
2) Add a TXT record for barracuda.gilstermarylee.com that lists the
SPF rules.  (http://www.spfwizard.net/ can be helpful here)
3) Consider a TXT record for DOMAINKEYS. This isn't so important these
days, but you might as well look into it.  (
https://www.socketlabs.com/domainkey-dkim-generation-wizard/ may help)
4) Review the A record for barracuda.gilstermarylee.com and see if you
really want it pointing to 75.149.203.77.  I think this is a wildcard
and probably not what you want.  Odds are, it should be set to the
same as the MX record in step 1.
5) Recognize that SMTP sucks and it shouldn't take 15 years of
routing, SMTP and DNS experience just to set up a freaking server.
Outsource your email to someone else and wash your hands of the whole
stinking mess of it.

-Josh


On Tue, Nov 25, 2014 at 9:46 AM, Jonathan A. Kollasch
<jakllsch at kollasch.net> wrote:
> On Tue, Nov 25, 2014 at 09:38:09AM -0600, L. V. Lammert wrote:
>> Trying to assist a friend in fixing an issue with their email system, ..
>> they appears to be using a Barracuda appliance (per hostname), yet it
>> appears to not be sending a valid hostname:
>>
>> ================
>>
>> Nov 23 03:38:37 mx2 postfix/smtpd[5951]: NOQUEUE: reject: RCPT from
>> unknown[66.186.99.236]: 450 Client host rejected: cannot find your
>> hostname, [66.186.99.236]; from=<rhayden at gilstermarylee.com>
>> to=<lvl at omnitec.net> proto=ESMTP helo=<barracuda.gilstermarylee.com>
>>
>> ================
>>
>> I do know they are switching providers, but I do not think that would
>> affect the issue. Any suggestion on how to troubleshoot this problem?
>
> This sounds like 66.186.99.236 doesn't have reverse DNS records.
>
>         Jonathan Kollasch
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