It (SPF) is performed before greylisting (which needs the host, mail from and rcpt to) so the SPF check actually happens just before
the greylisting if the SMTP switch is turned on. However the destination user (rcpt to) is checked first to see if the user exists
and if not, then the email is rejected there before doing the SPF check. Actually DNSBL checks are done first of all if the SMTP
flag is set.
There is a ton of configurability as what is checked, when and what to do if a
check fails.
There is also an add-on that allows users to receive a report on what Spam they
didn't receive. If it was not rejected during SMTP
it's archived before being discarded. In the report there's a link that allows
a user to retrieve a discarded email. Keeps users
from being overly concerned about what email they're not getting. It's a very pretty/professional looking report with statistics,
charts and graphs. There's also an admin report that has all kinds of system level information. I also get a report every time a user
recalls something (this can be turned off). This all helps keep the Spam tuning
refined.
It's a very clean, simple to install package with a nice clean GUI interface
(wish it were WEB based however) that's easy to use.
I have other mail servers (actually mail hubs) that use Sendmail, MailScanner, SpamAssassin and ClamAV. Yes with all the add-ons
they do almost all the same things. Also once their up and running, things seem to work very well. There's a lot more to
installation, configuration and upgrading. And I have not yet found as good a reporting tool for that combination.
Also XWall is written specifically to interface with Exchange and I have not
seen anything for Linux that does that as well (yet).
Just my .02cents if it's for Exchange.
Other mail servers I support are CommuniGate Pro for Linux which is a very good mail server (however it's a bit expensive) and I
front end them with multiple mail hubs based on Sendmail (also running on Linux).
Scott Kitterman wrote:
-----Original Message-----
From: Dennis Willson [mailto:taz(_at_)taz-mania(_dot_)com]
Sent: Monday, August 22, 2005 2:04 PM
To: spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
Subject: Re: [spf-discuss] OT: SMTP pre-filter server
There is a configuration option that allows you to use SPF during the SMTP
conversation. I use that setting and it then tests SPF before the
greylisting.
Thanks. I guess their web site could be clearer then.
If that works for you, that's great, but generally speaking, SPF is a pretty
heavyweight test. I'm not sure where in the scheme of things you are doing
this, but it's not generally adviseable to do SPF checks until after RCPT
TO: and you've validated RCPT TO:. Doing SPF up front may work for you, but
in many cases it's had a negative effect on performance.
Scott K
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