Re: [courier-users] "Notice: mail delivery status" messages sent to Postmaster on secondary MX delivery failures?

[Greg E. <ea...@is...>]

On Jul 27, 2005, at 10:23 AM, "Tim Hunter" <ti...@br...> wrote:
> Flavio Stanchina said:
>> Sam Varshavchik wrote:
>>>> Is there any way to configure Courier to *not* generate DSNs
>>>> for this kind of situation?
>>>
>>> No.  This is how SMTP is supposed to work.
>>>
>>> You will have to either stop using a secondary MX, or reconfigure 
>>> your spam filter to drop unwanted mail, instead of rejecting it.
>>
>> That's fine, but how does one set up a backup MX without a secondary 
>> MX?
>>
> a backup MX is not really needed anymore, everyone on the Internet
> that is running a mailserver should have a good enough connection to
> recieve mail in a timely fashion.  Even if your mailserver is not
> reachable for over a day, the sending mailserver will queue it up for
> typically many days before you will start losing mail.

I have my work mail server be a secondary (10) MX for my home mail
server (5) because (a) it's convenient; and (b) it means I get to
keep control over my own e-mail.

Here's an actual scenario where it came in handy: I went on a trip
overseas for 2 1/2 weeks from Christmas 2001 into January 2002,
and at some point during the trip, my home ISP kindly reconfigured
their network and all of my hosts were given new IP addresses
without me knowing what they were.

Because my mails piled up on my work mail server, I was not
only able to see what they were from halfway across the world
but I was also able to hold them in abeyance 'til I got back and
prevent them from being auto-barfed back at the 4 or 5 day mark.
I considered this extremely useful.

(As for rejecting SPAM at the front door, I only do it for
blatantly high SpamAssassin scores, and I've spent enough
time tuning my SpamAssassin rules that I don't get any FPs
anymore.  I don't like to accept and delete because that
way there is no feedback that tells the spammer it was simply
rejected outright.  Perhaps I'm delusional, but I'm convinced
that my total rate of incoming SPAM has lessened due to this
reject-at-the-front-door policy.)

Anyway, I think I might have to take Sam's suggestion and
drop the secondary MX'ing.  The same scenario occurs when
mail comes in that generates 550 User unknowns as well
(i.e., usually mis-targeted SPAM that uses a bad address).

What baffles me however is why there's been this sudden
increase in these DSNs since I moved my Courier server into
full production use.  The machine has been my secondary MX
all along, for well over a year, and then I moved it into
place as our "real" mail server and suddenly it's DSNing
all over the place - it doesn't make sense.  I did not
change anything fundamental in the Courier setup that would
impact this; just changed the machine name everywhere I
could find it, with a few tweaks to the aliases.  Surely
I should've been getting them all along; not just now?

	- Greg