Re: mail sorting tool
On Sun, 07 Jan 2001 15:48:38 +1100, Craig Sanders writes:
>> Does your ISP offer some kind of smtp-queuing? We do (mail is put into
>> a queue, there?s a script watching the dialin-logs, when it sees that
>> there?s a queue for that user, sendmail is started with on-the-fly
>> rewritten options for that queue, eg smarthost set to the dynamic IP).
>>
>> Way easier than UUCP (imho) and even working for
>> exhaust^Wexchange-boxes at the customer.
>
>sounds like a complicated and not very reliable way of avoiding the
>simplicity and reliability of uucp.
>
>like MX records pointing to dynamic DNS entries, this still has the
>small chance of delivering the mail to another system - e.g. when the
>client logs off and another user immediately logs in and gets the same
>IP address. SMTP isn't appropriate for delivering mail to dynamic IP
>addresses.
No, this isn´t possible. Scanning and starting the queue-run costs ~4
seconds, whereas the IP-address will not be given out for 5 minutes
once assigned (this is to make finding spammers easier, most
timestamps in complaints aren´t that accurate).
>it also doesn't scale very well - it clutters up (and slows down) the
>ISP's mail queue with mail that would be better stored in a uucp queue.
>
>one obvious big difference is that the mail queue is scanned regularly
>(and also when "sendmail -q" or similar command is run). compare that
>to uucp where the mail is just dumped into the client's uucp queue
>directory and basically ignored until the client logs in to download it
>(ignored, that is, except for a nightly cron job to bounce mail that
>has been waiting in the queue for too long because the client hasn't
>bothered to log in for a fortnight)
>
>this can be particularly bad if you're using sendmail (which only has
>one queue directory) rather than, say, postfix (which has a multi-level
>queue directory hash). in either case, it still takes a lot longer to
>scan a few thousand queued messages than a few hundred.
we _use_ sendmail, but with handwritten rules, every client has it´s
own queue-directory, which is why the sendmail-configuration for the
queue-runs is built on-the-fly ;-) . the queue isn´t scanned regularly
because many clients have periods of weeks of not dialing in.
I´m not saying that it´s easy to build on the ISP-side, but it´s easy
for the customer and makes a great product.
>another obvious difference is that if one client ends up with thousands
>of small mail files in the one directory then the resulting speed
>slowdown (on pretty nearly any filesystem except for reiserfs) only
>affects that client and not every other client as well.
see above.
>add to that the fact that the uucp queued mail can be stored compressed
>with gzip, or can be compressed and encrypted on-the-fly if you're using
>stunnel and openssl to wrap the uucp transfers and it's hard to see any
>valid reason for using smtp to do a job that uucp was designed to do.
>smtp delivery to dynamic IP hosts just isn't very reliable. it can be
>kludged to be *almost* reliable but "almost reliable" is just another
>way of saying "not reliable" and that's not really good enough for mail.
it is perfectly reliable when you design and build it with care. your
objections are valid, but we had them (and a few others) in mind when
setting it up. add that and the fact that we still offer uucp also,
but sold the last account mid-´99 ...
cheers,
&rw
--
/ Ing. Robert Waldner | Network Engineer | T: +43 1 89933 F: x533 \
\ <Waldner@KPNQwest.at> | KPNQwest/AT | Diefenbachg. 35, A-1150 /
Reply to: