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Posted to users@spamassassin.apache.org by "Stewart, John" <jo...@artesyncp.com> on 2006/03/15 16:53:07 UTC
Importance of SMTP gateway reverse lookup domain?
We've got an outgoing SMTP gateway of bratwurst.heurikon.com (heurikon.com
being an old domain name, and I've never bothered with trying to update the
domain for all of our infrastructure machines), but our outgoing domain on
our emails is artesyncp.com (and that may change soon as well).
I'm wondering if this is something that SA (or, perhaps more importantly,
other spam packages) will flag as a possible spam indicator, or is this
common enoough (email and SMTP gateways having mismatched domains) that is
is not worth worrying about?
Also, and this is perhaps a bigger issue, if we were to set up a seperate
SMTP server for only outgoing mail (and not incoming), would it be an issue
if this outgoing SMTP server is not in the MX records for the artesyncp.com
domain.
So, for example, if you do an MX lookup on artesyncp.com, you will see that
bratwurst.heurikon.com is our MX record, so this matches. However, if we had
a new host, not on our MX list, doing the outgoing mail delivery, would this
be a likely indicator of spam?
It's not something we've needed to do yet, but might want to in the future.
If it is likely to be an issue, we might just set the email to continue to
flow through bratwurst if necessary.
thanks!
johnS
Re: Importance of SMTP gateway reverse lookup domain?
Posted by Michael Monnerie <m....@zmi.at>.
On Donnerstag, 16. März 2006 08:16 David B Funk wrote:
> No, but in the SPF record for "artesyncp.com" you should list the
> names of the outgoing SMTP servers so SA (and the world) will know
> that they are 'permitted' to source mail for "artesyncp.com".
You can look at http://openspf.org there's a web based tool that helps
you setup SPF records for your domain.
mfg zmi
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Re: Importance of SMTP gateway reverse lookup domain?
Posted by David B Funk <db...@engineering.uiowa.edu>.
On Wed, 15 Mar 2006, Stewart, John wrote:
> Also, and this is perhaps a bigger issue, if we were to set up a seperate
> SMTP server for only outgoing mail (and not incoming), would it be an issue
> if this outgoing SMTP server is not in the MX records for the artesyncp.com
> domain.
>
> So, for example, if you do an MX lookup on artesyncp.com, you will see that
> bratwurst.heurikon.com is our MX record, so this matches. However, if we had
> a new host, not on our MX list, doing the outgoing mail delivery, would this
> be a likely indicator of spam?
No, but in the SPF record for "artesyncp.com" you should list the names
of the outgoing SMTP servers so SA (and the world) will know that they
are 'permitted' to source mail for "artesyncp.com".
--
Dave Funk University of Iowa
<dbfunk (at) engineering.uiowa.edu> College of Engineering
319/335-5751 FAX: 319/384-0549 1256 Seamans Center
Sys_admin/Postmaster/cell_admin Iowa City, IA 52242-1527
#include <std_disclaimer.h>
Better is not better, 'standard' is better. B{
Re: Importance of SMTP gateway reverse lookup domain?
Posted by mouss <us...@free.fr>.
Stewart, John a écrit :
> We've got an outgoing SMTP gateway of bratwurst.heurikon.com (heurikon.com
> being an old domain name, and I've never bothered with trying to update the
> domain for all of our infrastructure machines), but our outgoing domain on
> our emails is artesyncp.com (and that may change soon as well).
>
> I'm wondering if this is something that SA (or, perhaps more importantly,
> other spam packages) will flag as a possible spam indicator, or is this
> common enoough (email and SMTP gateways having mismatched domains) that is
> is not worth worrying about?
>
The MTA should have a matching rdns (double DNS check). so if its IP is
192.0.2.25. a reverse lookup of this IP must return at least one
hostname. And a forward lookup of one of these hostnames must return the
IP address. In short,
one_of_IPs(one_of_names(IP)) = IP
> Also, and this is perhaps a bigger issue, if we were to set up a seperate
> SMTP server for only outgoing mail (and not incoming), would it be an issue
> if this outgoing SMTP server is not in the MX records for the artesyncp.com
> domain.
>
MX is for receiving mail. It has nothing to do with mail sending.