Sendmail on a LAN

JD jd1008 at
Tue Aug 17 21:25:07 UTC 2010

  On 08/17/2010 01:27 PM, Gordon Messmer wrote:
> On 08/17/2010 09:33 AM, JD wrote:
>> Re:  a.b.c.d ==>
>> and ==>   a.b.c.d
>> does not seem to apply to the google smtp server I use for Thunderbird.
> You did your test entirely backward.  You did a forward lookup first,
> and then checked the PTR of the IP which was returned.  There is no
> requirement for a PTR to match every hostname that resolves to its IP
> address.
> Let's finish your test:
> $ host
> is an alias for
> has address
> The result of this test merely identifies an IP address.  Now, let's
> test to validate that the IP returns a PTR that resolves to the same IP:
> $ host
> domain name pointer
> $ host
> has address
> Yep, totally valid.  That IP address has a PTR record, and the hostname
> contained in that PTR resolves back to the same IP address.  This host
> is properly configured.
>> So, Thunderbird client does not seem to mind that
>> reverse lookup does not match the name
> Clients rarely do.  It's the servers to which you're going to try to
> deliver mail that will mind.
I see! Thanks for the heads up!
At any rate, I am having serious problem with an unwieldy router.
I just posted a message about that.

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