RE: DNS Reverse Lookup + Drop connection
- From: "Militello, John" <jmilitello@xxxxxxxxxxxxx>
- To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
- Date: Thu, 5 Feb 2004 15:55:25 -0500
Last month AOL decided it would accept our messages but drop the mail
into quarantine. I called them and they notified me that I had to have
PTR records for my servers. This must be a recent change because we
where able to pass mail to them up until a month ago. Another name for
the records are "in-addr.arpa delegation" or "reverse" IP resolution...
going from the IP address back to a hostname. Another note is that it
actually does the lookup backwards using the last octet first then the
second and so forth.
John Militello
Wilmorite Property Management, LLC
Ciber Inc.
Rochester NY
-----Original Message-----
From: John Tolmachoff (Lists) [mailto:johnlist@xxxxxxxxxxxxxxxxxxx]
Sent: Thursday, February 05, 2004 3:43 PM
To: [ExchangeList]
Subject: [exchangelist] RE: DNS Reverse Lookup + Drop connection
http://www.MSExchange.org/
Not the best of ideas to drop/dis-allow incoming messages based on no
PTR
record.
Yes, all sending servers should have a PTR record.
1. Auto notices, such as order confirmations, error notifications and so
forth often come from web servers or devices that are not internet
facing
per-se and do not have a PTR record.
2. Depending on volume, checking for a PTR record at the time of and
during
a incoming transmission can be resource intensive.
3. Not all companies/admins are smart enough to properly configure their
configuration and may not have a PTR record.
4. Some ISPs will not create a PTR record for you, or delegate authority
to
you so you can create the PTR records. (Of course, any one operating an
e-mail server should not be using these ISPs, but it does occur.)
John Tolmachoff
Engineer/Consultant/Owner
eServices For You
> -----Original Message-----
> From: Hermano JS. Queiroz [mailto:hjsqueiroz@xxxxxxxxxxxxxxxxxx]
> Sent: Thursday, February 05, 2004 12:23 PM
> To: [ExchangeList]
> Subject: [exchangelist] DNS Reverse Lookup + Drop connection
>
> http://www.MSExchange.org/
>
> Hi All,
>
> I would to know if someone can give me a clue about DNS reverse
> lookup with exchange. I already check the Perform reverse DNS lookup
on
> incoming messages (Advanced Delivery) but I really want to drop all
> connections that doesn't have their name resolved. Am I dreaming with
> something or Exchange 2K SP4 cannot do it or whatelse needs to be
done.
>
> TIA,
>
> Hermano
>
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