Re: Reverse Lookup & Spam

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Lanwench [MVP - Exchange] (lanwench_at_heybuddy.donotsendme.unsolicitedmail.atyahoo.com)
Date: 12/09/04 

Date: Wed, 8 Dec 2004 22:45:21 -0500

cldpeak wrote:
> Is it common for various corporations to use reverse lookup (ptr
> records) to verify e-mail and drop those that don't resolve as spam?

It's starting to be more common, asinine though I find it.
>
> I was planning to start running my own DNS servers so that I could
> allow clients more freedom in choosing their ISP without me dealing
> with the old ISP maintained DNS records.

I wouldn't bother as you need two extra DNS servers on your network to do
this and you're unlikely to have as robust a network/Internet connection as
a hosting company does - if your ISP isn't responsive, try moving to someone
else who's better.
>
> However, I remember a time when a client could not send mail (to GAP
> inc. in particular) turned out they use reverse lookups and would not
> accept mail until I had the ISP create the PTR records.

The ISP, not the DNS host. Unrelated....
>
> So, if running my own DNS I would not have the authority to create
> the PTR record for an IP address that belonged to an ISP right? I'll
> still have to pay the DNS hosting records with the ISP unless there
> is a way around it...

Not really relevant, because as I said you wouldn't create the reverse
lookup for your public IP anyway - whoever owns that netblock would do it.
>
> opinions?

Relevant Pages

  • Re: Usage Report show IP addr instead of computer names
    ... I didn't have Reverse Lookup configured for all of my subnets. ... The reverse DNS look-up is only query DNS server, ... Can you see the PTR record for the unresolved IP address, if not, please ... | the reverse lookups at 4:30, will that cause the Usage Report to identify ...
    (microsoft.public.windows.server.sbs)
  • Re: cnames stop resolving
    ... Wait a minute, if you have a asdf.com zone, the external.asdf.com CNAME ... DNS does not cache records it is authoritative for. ... PTR records and A records are not related except by coincedence. ... only time a CNAME is brought into play in a reverse lookup is when a PTR is ...
    (microsoft.public.windows.server.dns)
  • Re: IIS email being rejected by some domains.
    ... If your ISP is managing your forward DNS as you indicated, then they are surely responsible for your reverse DNS (PTR) zone as well, and it was lazy of the ISP tech to not take note of this. ... smtp server name from smtp1.example.local to the fqdn mail.example.com. ...
    (microsoft.public.inetserver.iis.smtp_nntp)
  • Re: Outbound mail
    ... Yes the ISP is responsible for the PTR after you are setup and running. ... Not the DNS host of the domain? ... First Check to see if Port 25 is blocked either outbound inbound or both ...
    (microsoft.public.windows.server.sbs)
  • Re: Comcast DNS Issue
    ... I believe your ISP has to do it. ... Since I am a newbie, ... > what you are saying is that Comcast probably needs reverse DNS enabled. ... Does this mean I should create a new PTR record on my DNS ...
    (microsoft.public.exchange.connectivity)