>What's the difference between HELO and ELHO? When a SMTP session is started, the first command the connecting client is supposed to give is the hello command. This identifies the client to the server.
The original SMTP spec used HELO. Later, when the SMTP command set was extended with a bunch of optional abilities (things like mail authentication) it was decided there had to be a way to let the server and client know if each other were trying to use the old set or new set of commands. Since the new set was known as Extended SMTP, they made a new hello command which is EHLO. It is only used so the server and client can determine which set of SMTP commands each other is planning to use. If a server doesn't support E-SMTP, then it should refuse the EHLO command, at which time the client can retry using the HELO command. Conversely, if the client uses the HELO command to start, the server knows it shouldn't bother giving things like the ESMTP welcome banner that lists out a bunch of the commands and structures it can use (because that may just confuse the client that isn't expecting to see such a response). -chris <http://www.mythtech.net> ___________________________________________________________________________ To unsubscribe send a mail message with a SUBJECT line of "unsubscribe" to <[EMAIL PROTECTED]> or <[EMAIL PROTECTED]>
