[HLUG] Exim 4.50 on Debian 3.1 external greet_pause?

[Mark Broadbent]

Hi John,

On 29/01/07, John Hedges <john at drystone.co.uk> wrote:
> On Mon, Jan 29, 2007 at 04:01:44PM +0000, Mark Broadbent wrote:
> > [...]
> >
> > Well that's the point of a secondary, to provide a spool in the event
> > of the primary going down or being inaccessible, not for load
> > management (for this you would define two mail servers at the same MX
> > priority).  Doing this guards against the danger of badly configured
> > or misbehaving sending hosts that do not or cannot resend/retry, plus
> > it prevents senders from seeing warning messages when the email has
> > been delayed.
>
> Thanks Mark. Maybe I am less than bomb-proof. However I'm still not
> convinced that the (im)probability of receiving mail from a broken
> sender when your primary is down warrants maintenance of a second mail
> server. Perhaps it's a bit hard line but it's better not to pander to
> broken/misconfigured senders. You never know, it might prompt them to
> get their servers fixed :) And as far as the warning messages are
> concerned, aren't they useful to the sender?

I greatly depends on your circumstances, for me, my primary is located
in my house and is off most of the time so I want the backup to
collect mail and hold it quietly for upto 2 weeks (like when I go on
holiday).  For a business who relies on email then you have no option
but to make it as easy and bombproof as possible for your customers to
send you email.  But for everyone else, it won't matter.

> If your secondary can deliver mail, then fine - it's obviously useful in
> that you are improving availability, but just to spool seems pointless
> to me.

Very rarely would a secondary actually deliver mail (as I said before
it would be a redundant primary if it did), it's a good way of
reducing the delivery delay for email that was delivered whilst you
were off-line. Depending how long the primary is off-line, it could
take 1-2 days to actually receive all the stored email when relying on
the sending server to retransmit.  Again this highly depends on the
sending servers configuration.

Basically what I'm getting at is that it a defensive set-up to guard
against other peoples mistakes.

Thanks
Mark

-- 
Mark Broadbent
* http://www.wetlettuce.com/