# SMTP Nmap script: [smtp-open-relay](https://nmap.org/nsedoc/scripts/smtp-open-relay.html) `telnet 25`

Command	Description
`AUTH PLAIN`	AUTH is a service extension used to authenticate the client.
`HELO`	The client logs in with its computer name and thus starts the session.
`MAIL FROM`	The client names the email sender.
`RCPT TO`	The client names the email recipient.
`DATA`	The client initiates the transmission of the email.
`RSET`	The client aborts the initiated transmission but keeps the connection between client and server.
`VRFY`	The client checks if a mailbox is available for message transfer.
`EXPN`	The client also checks if a mailbox is available for messaging with this command.
`NOOP`	The client requests a response from the server to prevent disconnection due to time-out.
`QUIT`	The client terminates the session.

## Tools Metasploit (msfconsole) module: `scanner/smtp/smtp_enum` [smtp-user-enum](https://www.kali.org/tools/smtp-user-enum/) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.rtlcopymemory.com/footprinting/smtp.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.