RE: DNS Reverse Lookup + Drop connection

  • From: "John Tolmachoff \(Lists\)" <johnlist@xxxxxxxxxxxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 5 Feb 2004 12:42:37 -0800

Not the best of ideas to drop/dis-allow incoming messages based on no PTR

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
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
> 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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