The SMTP protocol includes many interactions back and forward between the sending and recipient agent. For example, for a multi-recipient message, the recipient addresses are sent one at a time, with an acknowledgement from the recipient before the next recipient name can be sent. What is the disadvantage with this, and how can it be overcome using facilities provided by existing standards?
turnaround takes time, so sessions will take longer time to complete. Methods
to overcome this: Send the next command without waiting for response on
the previous command. This is often called "Pipelining". Disadvantage: If
something goes wrong, you will have to retract to the last successful command.
You should not do this unless you have agreed with the server to do this,
and not all mail servers do not support pipelining. There is an ESTMP method
of indicating if you want to use pipelining.
List of exam questions