At 1:22 am -0400 10/8/2008, Hector Santos wrote:
Further it says: ....... As with temporary error status codes, the SMTP client retains responsibility for the message, but SHOULD not again attempt delivery to the same server without user review of the message and response and appropriate intervention.That is a clear cut statement that clients SHOULD not try again without some special human review - completely outside the automated process the state machine provides.
It says "message", singular. As far as I am concerned (and this is reflected in my MTA implementation) multiple RCPT TOs is multiple messages. The optimized case where multiple messages with identical bodies are sent over a single session with multiple RCPT TOs and a single copy of the message body should not be treated any differently from if all those messages were sent independently.
The standards certainly don't specify any different treatment for the optimized case.
Glenn.