When a firewall performs email filtering, which of the following email transfer protocols does it support?

Question

Options

• ASMTPS
• BSMTP
• CP0P3
• DIMAP

• A
  83% (19)
• B
  4% (1)
• C
  4% (1)
• D
  9% (2)

Explanation

SMTPS (A) is correct because firewalls that perform email filtering operate at the transfer layer - inspecting messages as they move between mail servers - and SMTPS is the secure (SSL/TLS-encrypted) version of SMTP designed for exactly that role. Modern firewall email filtering solutions support SMTPS to perform deep packet inspection on encrypted email traffic via SSL/TLS offloading.

Why the distractors are wrong:

• B (SMTP): Plain SMTP (port 25) is the predecessor protocol without encryption; modern email filtering appliances target the secure variant (SMTPS) rather than unencrypted transfers.
• C (POP3): POP3 is an email retrieval protocol used by clients to download messages from a mailbox - it's not involved in mail transfer between servers.
• D (IMAP): IMAP is also a client-side retrieval protocol for accessing and syncing mailboxes; like POP3, it plays no role in server-to-server mail transfer.

Memory tip: The "S" in SMTPS stands for Secure - think Secure Mail Transfer = the protocol firewalls filter on. A simple rule: SMTP/SMTPS = sending/transferring; POP3/IMAP = picking up your mail. Firewalls filter what's in transit, not what's already in your inbox.

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