Automated SMTP interaction sequence consistent with open-relay validation or spam delivery testing. The client performs a full transaction flow (EHLO → RSET → MAIL FROM → RCPT TO → DATA → QUIT) and submits a minimal test message containing known probe markers such as t_Smtp.LocalIP. This pattern indicates scripted activity attempting to confirm whether the server allows unauthenticated message relaying or outbound mail submission. Such behavior is commonly observed from spam bot infrastructure validating targets before larger abuse campaigns.

Automated SMTP interaction performing a minimal capability check by issuing EHLO followed by a STARTTLS upgrade request and immediately terminating the session. This pattern is commonly associated with internet-wide scanners, security research crawlers, or opportunistic bots verifying whether an SMTP service supports encrypted communication. The absence of authentication attempts or message submission indicates reconnaissance or service fingerprinting rather than active abuse.