Hi,

PMDF 6.2 on OpenVMS Alpha 7.3.

My servers act as an SMTP firewall/relay for a customer site. There is a
PMDF channel dedicated to this customer.

At the customer's request, I have these limits on the customer's channel:

blocklimit 6000 sourceblocklimit 10000

i.e. PMDF won't attempt to send more than 6MB (approx) to their server nor
accept more than 10MB (approx) from their server.

My problem is that when an external user sends a large email to this
customer, my PMDF SMTP server accepts the message then bounces it when it
tries to enqueue the too-large message to the customer channel. So I've
accepted, paid for and stored a large file for no good reason.

For example, here's the sequence of log entries from a recent case:

27-Oct-2004 18:40:38.17 20e0182b.25b.877 tcp_local conversion E 8097 sender@domain.com.au rfc822;recipient@customer.com.au
27-Oct-2004 18:42:41.41 21002bfb.0 conversion pmas E 8136 sender@domain.com.au rfc822;recipient@customer.com.au
27-Oct-2004 18:42:41.65 21002bfb.1 conversion D 8097 sender@domain.com.au rfc822;recipient@customer.com.au
27-Oct-2004 18:42:57.62 20e055db.0 pmas process E 2 <> rfc822;sender@domain.com.au sender@domain.com.au
27-Oct-2004 18:42:57.62 20e055db.0 pmas process E 2 <> rfc822;postmaster@vsm.com.au postmaster@vsm.com.au
27-Oct-2004 18:42:57.87 20e055db.1 pmas D 8137 sender@domain.com.au rfc822;recipient@customer.com.au
27-Oct-2004 18:42:57.98 21002bfb.0 process tcp_internal E 4 <> rfc822;postmaster@vsm.com.au jeremy@eric.vsm.com.au
27-Oct-2004 18:42:58.18 21002bfb.1 process tcp_local E 4 <> rfc822;sender@domain.com.au sender@domain.com.au
27-Oct-2004 18:42:58.36 21002bfb.2 process D 4 <> rfc822;sender@domain.com.au sender@domain.com.au
27-Oct-2004 18:42:58.36 21002bfb.2 process D 4 <> rfc822;postmaster@vsm.com.au postmaster@vsm.com.au
27-Oct-2004 18:42:59.56 210025fe.2.1 tcp_local D 4 <> rfc822;sender@domain.com.au sender@domain.com.au
27-Oct-2004 18:43:00.05 20e055db.2.1 tcp_internal D 4 <> rfc822;postmaster@vsm.com.au jeremy@eric.vsm.com.au

Clearly the SMTP server didn't reject the message on the basis of the
message size, even though the destination channel has a block limit applied.
So if I want to prevent this happening in future I guess I need to put a
source block limit on my tcp_local channel. (And then decide what's
appropriate for *all* my customers.)

Does ESMTP provide for an SMTP client to inform the SMTP server of the
message size before transmitting the message? And do many clients (or
client sites) implement such a feature feature? Does PMDF implement such a
feature? Does MultiNet's SMTP client implement this feature? (My customer
runs MultiNet.)

Thanks,

Jeremy Begg

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