Gradual move to own mail server - strategy for noob
tedm at toybox.placo.com
Fri Jun 29 06:12:39 UTC 2007
> -----Original Message-----
> From: owner-freebsd-questions at freebsd.org
> [mailto:owner-freebsd-questions at freebsd.org]On Behalf Of RW
> Sent: Wednesday, June 27, 2007 5:51 PM
> To: freebsd-questions at freebsd.org
> Subject: Re: Gradual move to own mail server - strategy for noob
> On Wed, 27 Jun 2007 10:27:56 +0100
> Barnaby Scott <bds at waywood.co.uk> wrote:
> > Ultimately, but not yet, I want to start using the FreeBSD machine as
> > a proper mailserver - i.e. get a static IP address and point the MX
> > record hosted by my provider at it.
> It may not be sufficient to get a static IP address. If you wish to
> send out mail directly, you really need one with control of reverse
> DNS, since that's the criterion for getting out of dynamic
> address blocklists.
No, not exactly, this is a simplification. Some don't pay attention to
PTR's. The correct way is to resolve the hostname passed in the HELO
and compare the IP that results to the senders IP. Some lists do that
some don't when looking at removal requests.
You really need
a /24 subnet to be free of this. A number of the blacklists these days
are making the very ignorant assumption that if a single IP in a /24
is spamming, that it is OK to block the entire /24. The idea is if we
disrupt traffic enough the ISP will magically step in and do something
about it. I don't know exactly why these blacklist owners seem to have
on a /24, they probably got C's in their classes in school so have an
especial affinity for the deprecated-years-ago term "class C IP subnet"
Any ISP these days handing out static IP's has a mechanism for putting in
a PTR record.
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