Re: SMTP and new 822 interworking

[Shannon Yeh <yeh@xxxxxxxxx>]

Greg,

 > 
 > 1) If two hosts speak modified 8 bit SMTP, and a sender sends a 8 bit
 >    message, the sender has two choices.  They can either encode the
 >    message into 7 bits, and the receiver can decode it back to 8 bits, or
 >    the can send the message using efficient 8 bit transmission.
 > 
 > 2) If two hosts speak only 7 bit, and a UA needs to send an 8 bit 
 >    message, they must encode the message before sending it to the 7 bit
 >    SMTP.  The 7 bit SMTP will then exchange the mail as normal 7 bit
 >    mail, and the receiving UA will decode the message.
 > 
 > 3) If a 8 bit host speaks to a 7 bit host, either directly or as a
 >    gateway, it needs to speak 7 bit.  The conversion will be done by the
 >    modified SMTP with a new header line prepended to the message
 >    indicating that is has been encoded in the new format.
 > 
 > 4) If a 7 bit host talks to a 8 bit host, it can only speak 7 bit.
 >    The UA will decode the message back to 8 bits if needed.
 > 

	I believe that we can turn out an implementation soon one way or
	the other, if it is necessary to do the conversion/mapping.
	If the encode/decode transaction takes more than 10% of the normal
	message transaction time, what is the necessarity to do so, in terms
	of security/performance? Why don't we just use FTP to exchange
	mail, and forget SMTP? Then, we can build a user agent program to
	specify binary or ascii transfer mode. I am looking forward to seeing
	articles discussing about the benefit for such a big switch. If 
	there's no major improvement on security and performance, we will
	have to keep using the current text message trasfer protocol.

shannon
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