On Thu, 2006-04-27 at 22:36 +0200, Sandy Drobic wrote:
Hylton Conacher (ZR1HPC) wrote:
Carlos E. R. wrote:
The first SMTP sever may ask questions, of course. Any SMTP server in the chain, except the one of the destination address may ask for authentication of some sort; ie, your ISP SMTP server may ask for it, because it will _relay_ your mail to somebody else......
OK, understood. What tyoe of authentication could a SMTP server say 3 down the line ask for? Would its request be answered by the second SMTP server or would SMTP-3 try and contact the original dialup server which may not be currently connected?
Authentication, when it is required, will alway happen between the server that currently has the mail and the server that is contacted to receive the mail.
There's still the question of verifying the integrity of the content to the final recipient. That can be done by encrypting the payload, or by signing it. That avoids the recipient having to trust some unknown chain of hosts in the transmission path. Cheers, Dave