Request for assistance

John Abreau jabr at abreau.net
Tue Dec 17 23:19:48 EST 2002


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John Chambers <jc at trillian.mit.edu> writes:

> This isn't consistent with the behavior that I've seen  on  ANY  unix
> system.   The most common MTA, the /bin/mail program, always has a -v
> option that shows you the transaction.  In most cases, what it  shows
> you  is an immediate connection to the remote system, followed by the
> SMTP conversation.  When this finishes, the email has been delivered,
> and no local server was involved.

Not exactly. /bin/mail *always* pipes the message to a local instance 
of sendmail. The -v option is merely passed to the sendmail command line 
as it's invoked, and the transaction you see is coming from sendmail. 

> If this fails for some reason (e.g., you're offline), you get a  line
> saying that the message has been queued. This merely means that it is
> sitting in a directory (usually /var/spool/mail) on your disk. It has
> not  been handed to a server of any sort. 

The sendmail instance is being started by the /bin/mail process. It's 
not talking via SMTP to a preexisting sendmail daemon that's listening 
on port 25, so in that sense it's not talking to a "server". Regardless, 
it *is* still handing the message off to sendmail. 

> If you don't have a full-time connection, you do  need  a  server  on
> some fully-connected machine for incoming mail. (The UUCP folks had a
> solution to this, but the SMTP gang never learned about it.  ;-)  You
> still  don't need a local server for outgoing mail.  And in the usual
> unix setup, you don't use one.

The SMTP folks long ago defined "batched SMTP", which would write the 
SMTP transaction into a file, and then the sysadmin setting up the 
mail service would be responsible for devising a mechanism to transport 
such files to a better-connected peer. As I recall, it didn't see much 
use, mainly because people who needed that functionality were already 
using sendmail over UUCP to achieve store-and-forward mail transport. 


- --
John Abreau / Executive Director, Boston Linux & Unix
Email jabr at blu.org / WWW http://www.abreau.net / PGP-Key-ID 0xD5C7B5D9
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