Re: Does this mean reverse DNS was not setup?


"denoxis" <google@xxxxxxxxxxxx> wrote in message
news:1169844626.105902.169420@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

On Jan 26, 9:02 am, "Herb Martin" <n...@xxxxxxxxxxxxxx> wrote:
"denoxis" <goo...@xxxxxxxxxxxx> wrote in
messagenews:1169829994.442513.6450@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hello,

I have a dedicated server for hosting purposes. It runs on Windows 2003
(but I don't think my question is Windows 2003-specific). Web apps from
this server sends notification emails to visitors. Some of the emails
bounce back because of (I guess) reverse DNS issue:

smtp;450 Client host rejected: cannot find your hostname,
[my.servers.ip.number]Probably due to your not having the reverse PTR
record OR
to your SMTP server not using that same name as the HELO
name of the SMTP server (software.)

Thanks for the tip. I updated the email sender script so it updates the
HELO property to the FQDN that is specified in the
IIS6>SMTP>Delivery>Advanced. Otherwise it would use the computer name
with HELO by default.

Good. Very typical default settings.

Reporting-MTA: dns;MYSERVERNAME.MYISP.COM
As far I as understand it complains that my.servers.ip.number does not
resolve back to MYSERVERNAME.MYISP.COM even though other way around
works.It must resolve to the name used in your SMTP server software
(for most people to trust you.)

That name doesn't have to be in any way related to your actual server
name (what you call it) nor to your email domain name.

I tried the IP and it actually resolves to an ARPA address (which I
cannot specify as a FQDN in SMTP settings in IIS6 because it says it is
invalid.)What is it? What is your IP address? (We can check this for
you...)

As a paranoid admin I am masking IP numbers and stuff. Some hacker out
there maybe looking for rookie admins like me who doesn't know what is
going on and gives info about the server (IP number, OS and other
software running on the server.) Thank you for your understanding. :)

They are looking for you (and others) anyway -- if you are depending on
"obscurity for security" you are going to be compromised.

If your IP is on the Internet then ANYWAY can request that already. You
are merely keeping me (or others) from helping you.

So, ARPA address resolves to my.servers.ip.number,
MYSERVERNAME.MYISP.COM resolves to my.servers.ip.number, but
my.servers.ip.number resolves back to ARPA address, NOT
MYSERVERNAME.MYISP.COM.

Does this mean reverse DNS was not setup?Not if this command returns a
name:

nslookup IP.Your.SMTP.Server

Good, it does return a name. hostxx.xx.xx.xxx.maximumasp.com.

That's the name that goes into SMTP HELO field.

Maybe you are putting the "." on the end and the (stupid) software doesn't
allow that (technically ANY DNS name should support a terminating DOT
but many don't -- even though it is NOT a "FQDN" until that dot is added.)

--
Herb Martin, MCSE, MVP
http://www.LearnQuick.Com
(phone on web site)


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