--On Wednesday, 14 September, 2005 07:56 -0400 Hector Santos
<hsantos(_at_)santronics(_dot_)com> wrote:
...
All MUAs, including Outlook, have a MTA (SMTP client)
component. How else will it send mail to a SMTP server or
host?
Fascinating. Having been involved in writing an MUA or two
that did no such thing, and seen several others, I'm really
happy to hear about the "All" part. The two other models I'm
aware of are:
* the MUA uses some sort of API function or private
protocol to get the message content and headers (only)
to the MTA and the MTA constructs the envelope. This is
the classic story that motivates submission servers, but
submission servers whose "incoming" side is not SMTP.
* the MUA uses a different sort of API function or
private protocol to queue or send out a complete
message, with enough information capacity in those
functions to specify the behavior of the SMTP server,
including the envelope, queuing times/ behavior, etc.
Sigh
john