maillscanner/postfix saturates bandwidth :-(

Harondel J. Sibble mailscanner at
Mon Sep 24 21:08:36 IST 2012

On 24 Sep 2012 at 13:47, Dave Helton wrote:

> I would agree with Ian here, plus a couple other points.
> Your router is probably your dns server for internal to external resolving,

Why would you make that assumption?  IME, that just leads to problems, we 
NEVER use the router as a DNS server for a lan.

> and since it doesn't have a lot of memory, it has to look up each domain on
> the fly.  Not terribly bandwidth intensive for dsl, but it's still a lot of
> overhead... and slow. A caching dns server for the mail server would help a
> lot.

I'm pretty sure I already have a caching nameserver on this mailscanner box, 
but I will verify.  I have a vague recollection  that a different but related 
problem came up and the solution was to install a caching nameserver, that's 
our normal policy now, but this machine's probably been deployed long enough 
that it was prior to the caching nameserver being SOP.
> Second, you are probably subject to one of our best anti-spam mechanisms...
> greylisting.  That is, unless everyone on your mailing list has you on
> whitelist.... umm doubtful.  Again, bandwidth intensive.

Correct, as I was watching this unfold in realtime, I was thinking to myself, 
they are getting seriously tarpitted.
> Last, there are a lot of great mailing list programs out there that run
> specifically on an Apache server.  Even MailMan would work.  Both you and your
> customer could access the interface and you could do remote support for them,
> a nice selling point. This could also turn out to be one of those "the best
> laid plans" ordeal.  So give it some thought.

Good point
> My point is, take everything out of the hands of that Exchange server and put
> it in a controlled environment, meaning throttling, reporting, and easily
> accessible to you. I would also try and convince your customer that a LookOut
> distribution list is not an adequate substitute for the real thing since they
> have 'evolved' beyond it  ;-)

They do like to have sent items records of the outgoing emails, but with 
proper setup a MLM can easily generate a nice report (kinda like a fax 
machine) to show what was successfully delivered and such, so that's a great 

I actually don't know how they generated this on the Outlook side, they may 
even have been using some specialized application that plugs into outlook, 
I'll have a chat with them to determine that.
Harondel J. Sibble 
Sibble Computer Consulting
Creating Solutions for the small and medium business computer user.
help at (use pgp keyid 0x3AD5C11D)
(604) 739-3709 (voice)

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