Re: message size limitations

[Matti Aarnio <mea@nic.funet.fi>]

On Wed, Oct 02, 2002 at 05:27:08PM +0200, Marek Kowal wrote:
> Hi there,
> 
> I would like to vary maximum message size allowed by the smtp server based
> on the login of the sender from envelope address. The problem is, this quota

  The "login" you can get by doing AUTH, the MAIL FROM carried address
  makes no guarantee of anything.

  Once upon a time I did consider adding code to be able to parametrize
  the SIZE-limit value by source IP address.  (E.g. your dialup pools..)
  Oh.. There is even code, lots of it..

  The documentation is -- lacking.  Fix into  doc/guides/smtp-policy,
  and pasting here relevant passage:

	- smtp-policy.relay.manual
	- smtp-policy.relay
			Who can use us as outbound relay.

			Use here
				[ip.number]/maskwidth
			for listing those senders (networks) we
			absolutely trust.  Additionally you may give
			(at the same line) some attributes as parameters
			for this key entry:
				fulltrustnet +
				trustrecipient +
				maxinsize 30000000

			The first pair will accept any source address,
			and any recipient addresses that are fed to
			the server.

			The second will verify the source IP-address,
			but after that it will accept any recipient
			addresses.

			The third pair sets EHLO-reported "SIZE nn"
			parameter to be limited to 30 million bytes.
			(Or to global definition, if that is in range
			 of 1 thru 'nn'-1.)

   The parameter usage is purely advisorial.  It is used when formulating
   the EHLO response, not when checking e.g. MAIL FROM:<..> SIZE=
   parameter.

> is advertised by server after EHLO command, before MAIL FROM: command. Of
> course, I could advertise some big number there and refuse to process mail
> after "." from DATA command, but this will make users angry - first they
> will send huge mail over slow modem link for several minutes, and then they
> will be informed, that we are sorry etc... And the so called "user's
> positive experience" is an important issue for us and we'd rather not
> proceed in this direction.
> 
> Is there any way to force/advise client to send actual message size intended
> to be transmitted before DATA command, but after MAIL FROM: <>?

IF the client looks for EHLO reported SIZE value, then this technique can
be used to control the thing.  If not..  A code change is then (perhaps)
needed.

Of course the OE won't explain the remote system refusal in any
understandable way, which will cause your users to grieve more..


> Obviously, my main concern are Outlook Express clients, as they tend to be
> in biggest abundance out there in the real world ;-) Such cooperation from
> other relays would be feasible, but is not cruicial - i.e. I will loose some
> bandwidth, but at least the user will not wait, just the other server.

... however that is the pickle we all are in, OE is moron.

> Let me know, if you have any advices or experiences with that issue.
> 
> Cheers,
> Marek.

-- 
/Matti Aarnio	<mea@nic.funet.fi>
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