SMTP MAIL
This message flow simulates an SMTP session that sends one email message from the client to the server, and is intended to generate simple SMTP traffic between the MN and the Network Host node.
When control plane protocols are used, the message flow begins after Data Start Delay timer expires. The MN initiates the TCP connection and the Client Port and Server Port in the message flow define the ports used by both sides.
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The server begins the message sequence by sending the server greeting, indicating that it is ready to receive requests.
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The client requests a session with EHLO, and the server acknowledges the request.
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The server notifies the client that it supports chunking (the BDAT command).
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The server notifies the client that it supports pipelining.
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The client issues a MAIL to begin the mail transaction and transmits the FROM header. The server acknowledges receipt.
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The client continues the transaction with the TO header, and the server responds.
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The client issues a DATA to notify the server that it is ready to send the remainder of the email message, and the server confirms that it is ready.
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The client sends the first 100 bytes of the message content.
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The client sends the remaining 200 bytes of the message content.
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The client notifies the server that the message is complete, and the server responds.
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The client issues a QUIT to end the session, and the server signs off.
In the default configuration, the message flow will repeat once per second while the MN session is active. This assumes that the entire flow can be completed in one second. The flow must complete before the next iteration can begin, even if this results in a slower transaction rate.
Modifying the Message Flow
Since SMTP is a text-based protocol, you can easily modify the email message headers and the simulated message content, or import files to use as the message content. If you do modify the message, keep the following rules in mind:
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When using the DATA command, the message content must always finish with a period, and only a period, on the last line.
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You can simulate a session that sends multiple email messages by enclosing steps 5 — 10 in a transaction loop.
Pipelining can be achieved with SMTP by clearing the Wait for Response checkboxes in steps 5 — 10. The requests will be successively sent without waiting for server responses.
You can specify that random port numbers, in the IANA specified dynamic range of 49152 — 65535, be used by the client by entering a 0 for the Client Port.