On Fri, 13 Feb 2004, Dan Melomedman wrote:
> Steve Thomas wrote:
> > > SMTP is just a part of the infrastructure design, but it's not robust.
> >
> > I disagree. It was designed in such a way so that no message could ever be
> > completely lost, barring a catastrophic event (disk crash, alien invasion..
> > ;)
>
> You are not talking about SMTP, you are talking about the
> infrastructure in that sentence.
No, Steve has it right. He's talking about the formal specifications
of the Simple Mail Transfer Protocol (SMTP).
If you were to actually read RFC-2821, you would find implementation
INDEPENDENT statements of how mail should be handled.
It includes such statements as:
6.1 Reliable Delivery and Replies by Email
When the receiver-SMTP accepts a piece of mail (by sending a "250 OK"
message in response to DATA), it is accepting responsibility for
delivering or relaying the message. It must take this responsibility
seriously. It MUST NOT lose the message for frivolous reasons, such
as because the host later crashes or because of a predictable
resource shortage.
If there is a delivery failure after acceptance of a message, the
receiver-SMTP MUST formulate and mail a notification message.
Note that there's no language about HOW to go about doing this, just
statements of behaivors you must implement if you are going to
legitimatly claim to be an SMTP server.
So you could implement an SMTP system using scribes and signal flags,
so long as you met the specs for the resultant system characteristics.
I do agree that there are mail systems that are not robust, but
in a strict sense they cannot claim to speak SMTP unless they
comply with the letter of the specs.
--
Dave Funk University of Iowa
<dbfunk (at) engineering.uiowa.edu> College of Engineering
319/335-5751 FAX: 319/384-0549 1256 Seamans Center
Sys_admin/Postmaster/cell_admin Iowa City, IA 52242-1527
#include <std_disclaimer.h>
Better is not better, 'standard' is better. B{
