rfc 3030 comments...

[Franck Martin <franck at SOPAC.ORG>]

I'm just reading the rfc 3030 you made. I have been looking around for such protocol for large messages and I have been talking about it on the ietf at ietf.org mailing list.

I think the RFC could be even greater if it would allow to send chunks in separate sessions... Bigger will be the mail message, higher there will be a session error or connection drop. Therefore you have to be able to recover (like http and ftp protocol do)...

An extension to RFC3030 would be to have the server answering by a session ID with chunking and to use this ID in following BDAT commands in other sessions to recover from where the system left... Or other means of recovery... 

So if the session drops, the client issue a SESSION <sessionid> command where the server answers 250 ok to resume from <offset in bytes to resume from>

I know there is an experimental RFC out there that propose recovery, but it would be nicer if it was built in this RFC...

example:
   R: <wait for connection on TCP port
   S: <open connection to server>
   R: 220 cnri.reston.va.us SMTP service ready
   S: EHLO ymir.claremont.edu
   R: 250-cnri.reston.va.us says hello
   R: 250-PIPELINING
   R: 250-BINARYMIME
   R: 250 CHUNKING 345233
   S: MAIL FROM:<ned at ymir.claremont.edu> BODY=BINARYMIME
   S: RCPT TO:<gvaudre at cnri.reston.va.us>
   S: RCPT TO:<jstewart at cnri.reston.va.us>
   R: 250 <ned at ymir.claremont.edu>... Sender and BINARYMIME ok
   R: 250 <gvaudre at cnri.reston.va.us>... Recipient ok
   R: 250 <jstewart at cnri.reston.va.us>... Recipient ok
   S: BDAT 100000
   S: (First 10000 octets of canonical MIME message data)

   <connection lost>

   R: <wait for connection on TCP port
   S: <open connection to server>
   R: 220 cnri.reston.va.us SMTP service ready
   S: EHLO ymir.claremont.edu
   R: 250-cnri.reston.va.us says hello
   R: 250-PIPELINING
   R: 250-BINARYMIME
   R: 250 CHUNKING 452334
   S: MAIL FROM:<ned at ymir.claremont.edu> BODY=BINARYMIME
   S: RCPT TO:<gvaudre at cnri.reston.va.us>
   S: RCPT TO:<jstewart at cnri.reston.va.us>
   R: 250 <ned at ymir.claremont.edu>... Sender and BINARYMIME ok
   R: 250 <gvaudre at cnri.reston.va.us>... Recipient ok
   R: 250 <jstewart at cnri.reston.va.us>... Recipient ok
   S: SESSION 345233
   R: 250 ok to resume from 90000
   S: BDAT 10324
   S: (Remaining 10324 octets of canonical MIME message data)
   S: BDAT 0 LAST
   R: 250 90000 octets received from previous session
   R: 250 10324 octets received
   R: 250 Message OK, 100324 octets received
   S: QUIT
   R: 221 Goodbye
Cheers
Franck at sopac.org