hacktricks/network-services-pentesting/pentesting-smtp/smtp-commands.md

<details>

<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦 - </strong></a><a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️ - </strong> <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!

- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)

- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)

- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**

- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.

</details>


**Extracted from:** [**https://serversmtp.com/smtp-commands/**](https://serversmtp.com/smtp-commands/)

**HELO**\
It’s the first SMTP command: is starts the conversation identifying the sender server and is generally followed by its domain name.

**EHLO**\
An alternative command to start the conversation, underlying that the server is using the Extended SMTP protocol.

**MAIL FROM**\
With this SMTP command the operations begin: the sender states the source email address in the “From” field and actually starts the email transfer.

**RCPT TO**\
It identifies the recipient of the email; if there are more than one, the command is simply repeated address by address.

**SIZE**\
This SMTP command informs the remote server about the estimated size (in terms of bytes) of the attached email. It can also be used to report the maximum size of a message to be accepted by the server.

**DATA**\
With the DATA command the email content begins to be transferred; it’s generally followed by a 354 reply code given by the server, giving the permission to start the actual transmission.

**VRFY**\
The server is asked to verify whether a particular email address or username actually exists.

**TURN**\
This command is used to invert roles between the client and the server, without the need to run a new connaction.

**AUTH**\
With the AUTH command, the client authenticates itself to the server, giving its username and password. It’s another layer of security to guarantee a proper transmission.

**RSET**\
It communicates the server that the ongoing email transmission is going to be terminated, though the SMTP conversation won’t be closed (like in the case of QUIT).

**EXPN**\
This SMTP command asks for a confirmation about the identification of a mailing list.

**HELP**\
It’s a client’s request for some information that can be useful for the a successful transfer of the email.

**QUIT**\
It terminates the SMTP conversation.


<details>

<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦 - </strong></a><a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch</strong></a> <strong>Wed - 18.30(UTC) 🎙️ - </strong> <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!

- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)

- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)

- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**

- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.

</details>