nerdexam
EC-Council

312-50V12 · Question #297

What useful information is gathered during a successful Simple Mail Transfer Protocol (SMTP) enumeration?

The correct answer is C. The two internal commands VRFY and EXPN provide a confirmation of valid users, email. During successful SMTP enumeration, specific commands are used to identify valid user accounts and expand mailing lists, providing crucial information about a target's email infrastructure.

Submitted by alyssa_d· Mar 4, 2026Reconnaissance Techniques

Question

What useful information is gathered during a successful Simple Mail Transfer Protocol (SMTP) enumeration?

Options

  • AA list of all mail proxy server addresses used by the targeted host.
  • BThe internal command RCPT provides a list of ports open to message traffic.
  • CThe two internal commands VRFY and EXPN provide a confirmation of valid users, email
  • DReveals the daily outgoing message limits before mailboxes are locked.

How the community answered

(26 responses)
  • A
    4% (1)
  • C
    88% (23)
  • D
    8% (2)

Why each option

During successful SMTP enumeration, specific commands are used to identify valid user accounts and expand mailing lists, providing crucial information about a target's email infrastructure.

AA list of all mail proxy server addresses used by the targeted host.

SMTP enumeration using commands like VRFY and EXPN focuses on discovering user and alias information, not mail proxy server addresses.

BThe internal command RCPT provides a list of ports open to message traffic.

The RCPT TO command is used to specify the recipient of a mail message during the transfer process and does not provide a list of open ports, which is a function of network port scanning tools.

CThe two internal commands VRFY and EXPN provide a confirmation of valid users, emailCorrect

The VRFY (Verify) SMTP command is used to confirm the existence of a specific user or mailbox on the mail server, often returning their full email address. The EXPN (Expand) command similarly allows an enumerator to reveal the individual members of an email alias or mailing list, both providing confirmation of valid users and their email identities.

DReveals the daily outgoing message limits before mailboxes are locked.

SMTP enumeration commands do not expose internal server policy configurations such as daily outgoing message limits, which are administrative settings not revealed through standard command interactions.

Concept tested: SMTP enumeration for user and alias discovery

Source: https://datatracker.ietf.org/doc/html/rfc5321#section-4.1.1.3

Topics

#SMTP enumeration#VRFY#EXPN#reconnaissance#user enumeration

Community Discussion

No community discussion yet for this question.

Sign up to join the discussion
Full 312-50V12 Practice