On Wed, Dec 11, 2002 at 05:12:16PM +0000, Colin Watson wrote: | On Tue, Dec 10, 2002 at 09:49:41PM +0100, Robert Land wrote: | > On Tue, Dec 10, 2002 at 02:02:10PM -0500, Derrick 'dman' Hudson wrote: | > > On Tue, Dec 10, 2002 at 01:56:08PM +0100, Robert Land wrote: | > > | What I'm realy unsure about is if _all_ mail, even the one | > > | sent by the lowlevel 'mail' program goes through port 25. | > > | > > No. Many unix programs use a local pipe to deliver mail (eg mail, | > > mutt, cron and others). | > | > Is this what "batched smtp" refers to?
Not quite, but there is a similarity.
| Derrick's referring, I think, to calling /usr/sbin/sendmail with a
| single message on standard input.
Correct. I omitted any mention of BSMTP and other possibilities for
simplicity.
BSMTP consists of sending the client side of an SMTP data stream
through a pipe. It lacks, however, the lockstep verification that
SMTP allows.
For example, here is an SMTP session :
$ telnet dman.ddts.net smtp
Trying 65.37.45.154...
Connected to 65-37-45-154.nrp4.roc.ny.frontiernet.net.
Escape character is '^]'.
220 dman.ddts.net ESMTP Exim 4.05 (#8) Wed, 11 Dec 2002 15:55:50 -0500
HELO dman.ddts.net
250 dman.ddts.net Hello ros [24.97.91.241]
MAIL FROM:<[EMAIL PROTECTED]>
250 OK
RCPT TO:<[EMAIL PROTECTED]>
250 Accepted
DATA
354 Enter message, ending with "." on a line by itself
From: <[EMAIL PROTECTED]>
To: The-Bit-Bucket:;
Subject: test example
test
.
250 OK id=18MDu7-0005VX-00
QUIT
221 dman.ddts.net closing connection
Connection closed by foreign host.
Here is a sample BSMTP session :
$ /usr/sbin/exim -bS
HELO dman.ddts.net
MAIL FROM:<[EMAIL PROTECTED]>
RCPT TO:<[EMAIL PROTECTED]>
DATA
From: <[EMAIL PROTECTED]>
To: The-Bit-Bucket:;
Subject: test example
....
test
.
QUIT
$
Note that the data stream looks the same, except there is no response
from the server. The "batched" comes from the intent that the data
stream will be saved and then later fed into an MTA. An example
usage, as Colin indicated, is for a high-availability server to accept
the messages via SMTP (over TCP) and store the client machine's SMTP
commands in a file. The messages will be collected as they arrive,
then at some point the file will be transferred to a low-availability
server for delivery. The low-availability server receives all the
messages at once (as a "batch" job) via BSMTP.
| At any rate, all three of these mechanisms (TCP connection to port 25,
| BSMTP, plain sendmail) go through your local mail transport agent, as
| does any other normal means of sending mail in Unix.
This answers the real original question.
HTH,
-D
--
Consider what God has done:
Who can straighten what He has made crooked?
Ecclesiastes 7:13
http://dman.ddts.net/~dman/
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