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No PTR Record / Reverse DNS

I have had some issues sending email with the static IP assigned by my ISP, and I am considering forwarding all my outgoing mail to an external host, which will also filter the mail. However, I've been advised this system will insist on a valid reverse DNS lookup to accept email from our GroupWise system.

An example of one of the failed outgoing emails is the response here:
"Response: 554 cm7nec mx.talktalk.net axcCe5qYx52DX No PTR Record (TT105)"

How do I ensure that a correct PTR / Reverse DNS exists? Is it simply a matter of having the GWIA Hostname/DNS "A Record" name being fully correct / accurate?

Thanks in advance for any feedback

Jerome
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Re: No PTR Record / Reverse DNS

In article <zexec4.8b4nco@no-mx.forums.microfocus.com>, Zexec4 wrote:
> How do I ensure that a correct PTR / Reverse DNS exists? Is it simply a
> matter of having the GWIA Hostname/DNS "A Record" name being fully
> correct / accurate?


Your "A record" is independent of the PTR record for a given IP address.
The PTR record for your static IP needs to be assigned a PTR record by
your ISP. Just tell them you want the PTR for that IP to be the public
host name of your GWIA (to match it's A record)

The problems sending you've been having are very likely because of that
lack of a PTR record (and possibly some other things)

Of course you will want to test some of this. The standard tool is
NSLookup that can be a bit picky to use, or you can use the nice GUI
http://www.nirsoft.net/utils/dns_records_viewer.html
If mail goes strait to your GWIA, then just put your domain in, make sure
MX, A, and PTR are selected, and then you will see what is set.
Otherwise put in the host name, select both A and PTR.

Once that is sorted out, you might want to also set an SPF record as I've
seen a few places start getting picky about domains that don't have one.
An SPF record is basically you publishing in DNS where you email will
come from so that others can send email claiming to be from your domain.
This is done as a Text Record for your domain's DNS.
So if all your mail comes from your GWIA, and your MX points to it, a
very easy SPF record would be
"v=spf1 +mx -all"

for more on SPF, http://www.openspf.org/

There are other things that can be done, but these two are the big ones.


Andy of
http://KonecnyConsulting.ca in Toronto
Knowledge Partner
http://forums.novell.com/member.php/75037-konecnya
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Re: No PTR Record / Reverse DNS

konecnya;2473563 wrote:
In article <zexec4.8b4nco@no-mx.forums.microfocus.com>, Zexec4 wrote:
> How do I ensure that a correct PTR / Reverse DNS exists? Is it simply a
> matter of having the GWIA Hostname/DNS "A Record" name being fully
> correct / accurate?


Your "A record" is independent of the PTR record for a given IP address.
The PTR record for your static IP needs to be assigned a PTR record by
your ISP. Just tell them you want the PTR for that IP to be the public
host name of your GWIA (to match it's A record)

The problems sending you've been having are very likely because of that
lack of a PTR record (and possibly some other things)

Of course you will want to test some of this. The standard tool is
NSLookup that can be a bit picky to use, or you can use the nice GUI
http://www.nirsoft.net/utils/dns_records_viewer.html
If mail goes strait to your GWIA, then just put your domain in, make sure
MX, A, and PTR are selected, and then you will see what is set.
Otherwise put in the host name, select both A and PTR.

Once that is sorted out, you might want to also set an SPF record as I've
seen a few places start getting picky about domains that don't have one.
An SPF record is basically you publishing in DNS where you email will
come from so that others can send email claiming to be from your domain.
This is done as a Text Record for your domain's DNS.
So if all your mail comes from your GWIA, and your MX points to it, a
very easy SPF record would be
"v=spf1 +mx -all"

for more on SPF, http://www.openspf.org/

There are other things that can be done, but these two are the big ones.


Andy of
http://KonecnyConsulting.ca in Toronto
Knowledge Partner
http://forums.novell.com/member.php/75037-konecnya
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show your appreciation by clicking on the star below. Thanks!



Thank you Andy! Much appreciated.
Jerome
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Re: No PTR Record / Reverse DNS

zexec4 wrote:

>
> I have had some issues sending email with the static IP assigned by my
> ISP, and I am considering forwarding all my outgoing mail to an
> external host, which will also filter the mail. However, I've been
> advised this system will insist on a valid reverse DNS lookup to
> accept email from our GroupWise system.


This is a good resource to diagnose SMTP issues:
https://mxtoolbox.com/

> How do I ensure that a correct PTR / Reverse DNS exists? Is it simply
> a matter of having the GWIA Hostname/DNS "A Record" name being fully
> correct / accurate?
>
> Thanks in advance for any feedback
>
> Jerome


As more and more safeguards are put in place to deal with SPAM, valid
email may be rejected because of misconfigured SMTP servers and/or DNS
entries.

A simple workaround may be to forward outgoing email via your ISP's
SMTP servers which should be correctly configured.


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