-=> Quoting Kevin Campbell to Josh Fisher on 20 May 97 <=-
 >  -=> Quoting Kevin Campbell to All on 12 May 97 <=-
 
 >  KC> Does anyone have any info or source on programming for SMTP. I have
 >  KC> RFC821, but it has no information at all by the looks of things, on
 >  KC> how to recieve mail...
 
 >  It does. It is a transport protocol to transport mail from one host to
 >  another.
 KC> Yes, but the problem is how to get another host to initiate a
 KC> transation to you using SMTP. 
 >  I think what you're after is "How does a mail client app get the mail
 >  from a user's mailbox?" This is (almost universally) done using the
 >  Post Office Protocol Version 3, otherwise known as POP3, which is
 >  defined by RFC 1939.
 KC> Trouble is, I cannot use POP3 for the program I'm writing. I need to
 KC> be able to re-map domains, and POP3 only allows for a single address
 KC> (as far as I know). 
 OK. That is not done by SMTP. That is done within the DNS system. When
 an SMTP server receives mail that is destined for another domain, it
 attempts to trasfer that mail to the domain it is going to. It does this
 by querying a primary or secondary DNS server that is authorative for the
 destination domain. That DNS server then returns the IP address of the
 machine where that domain's mail should be sent.
 In the straight forward case, the SMTP server then establishes a socket
 connection to that machine and transfers the mail. In the real world,
 an SMTP server may transfer all or some external mail to a mail
 forwarder or smart host, which then transfers it to another host, etc.
 etc. until it is eventually transfered to the SMTP server for the
 destination domain. But in the end, it is the autorative DNS server
 for the destination domain that determines where the mail ends up.
---
---   Joshua Fisher
---   Cincinnati, Ohio  USA
---   jfisher@your-net.com
---
*SignIt 1.6* Signed on 05-23-1997
--- Blue Wave/386 v2.30
---------------