<reposting this since the first one didn't seem to go through>

Hello all; this is just a telltale about something I did setup lately
 
A friend of mine asked me if it was possible to setup ASSP to
serve multiple domains having different servers sitting in various
locations; after a bit of thinking I answered ... yes, it should be
possible and the whole thing started
 
The machine designated to run ASSP was a win2k3; so I went
on removing any unneeded service running on it and ensuring
that the IIS SMTP and the DNS services were installed; next I
proceeded downloading the ActivePerl setup and installing
ASSP and all the required modules, and then I installed clamav
 
At that point I configured all the pieces to properly route mail
the messages path was as follows
 
*inbound:
sender MTA -> ASSP -> IIS SMTP -> our MTA
 
*outbound
our MTA -> ASSP -> IIS SMTP -> recipient MTA
 
where btw "our MTA" designates one of the various servers
for which ASSP works as a spam filter and as a "smarthost"
the idea is the following; the incoming email is received by
ASSP which filters it as needed; if all ok, ASSP sends the
message to the IIS SMTP which enqueues it for delivery
 
The IIS SMTP is configured so that, each domain handled
by ASSP (our domains) is configured as a "remote domain"
and has its "smart host" (used for mail delivery for that given
domain) pointing to the MTA handling email for that domain
this way, the IIS SMTP handles all the mail routing toward
the various mailservers sitting "behind" ASSP; the same
happens for outbound email, although in this case the IIS
SMTP uses the regular "MX" mechanism to find out where
the outgoing email has to be delivered
 
going to DNS, here's a coarse example of how things are
configured; let's say we have "assp.mailfilter.org" which
is the name for the ASSP box; let's also say that ASSP
handles email for "foo.com", "bar.net", "baz.org" and
"taz.edu"; the MX records for those domains are setup
as follows
 
foo.com    IN MX 10    assp.mailfilter.org.
bar.net    IN MX 10    assp.mailfilter.org.
baz.org    IN MX 10    assp.mailfilter.org.
taz.edu    IN MX 10    assp.mailfilter.org.
 
at the same time the above domains have their own
mailservers which aren't published as "MX" but have
their entries in DNS, so that we may have
 
mail.foo.com    IN A    1.2.3.4
mail.bar.net    IN A    5.3.1.2
mail.baz.org    IN A    3.1.1.4
mail.taz.edu    IN A    8.7.5.3
 
this means that the IIS SMTP is configured so that (e.g.)
the "remote domain" "foo.com" will have all its mail
forwarded to "mail.foo.com" for delivery; the same goes
for the other domains; ASSP in turn is configured so that
the "sending IPs" used by the various domains to send
email to ASSP (used as smarthost) are considered by
ASSP as "local" so that our mail gets properly handled
by ASSP (automatic whitelisting and so on); since we're
at "sending"; the ASSP box has TWO public IPs; the first
one is the one used to receive email from external MTAs
and to send email to external MTAs, the second one is
configured so that the "relayport" is bound to this IP
on port 25 and this port in turn is firewalled so that
only "our mailservers" will be able to use it to send
email through ASSP

The above setup has now been working for quite a while 
and my friend is happy (the whole setup has been done 
for a no-profit organization having several offices 
around)
 
Just a final note/caveat; during the initial stage, I faced 
an issue that is, some messages with attachments didn't go 
through; at first I thought they were blocked by ASSP but that 
wasn't the case at all, so I started wading through the IIS SMTP 
logs and through the queued messages and found an "NDR" message
containing the following error
 
"554 5.6.1 Body type not supported by Remote Host"
 
I searched the 'net and found the culprit; the problem was that
one of the servers sitting "behind" ASSP had the "8bitmine"
extension disabled, while the IIS SMTP enables it by default
this means that the incoming mail passing through ASSP is
forwarded to the local IIS SMTP which accepts the 8bitsmime
encoding, but, when the IIS SMTP tries to delivery the email
to the destination server, the latter refuses the message due
to the lack of 8bitmime support and this in turn causes an NDR
to solve the issue I had two options; the first (and better) was to
to ask who managed that mailserver to enable the "8bitmime"
extension; the second was to follow the directions found inside
this MSKB document  
 
http://support.microsoft.com/default.aspx?scid=kb;[LN];Q262168
 
the problem with this second approach is that disabling the 8bit
support on the IIS SMTP means disabling it for ALL the domains
so it's an all or nothing solution; luckily enough, I was able to 
have the "not compliant" server config changed so that the
extension was enabled and the problem solved; at any rate
I thought that the above note may be useful for anyone facing
similar issues
 
well; that's more or less all, I just hope the above may be useful
to someone in need to setup ASSP to serve multiple domains
 
HTH


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