Which Port Is Used for Secure Email Submission?
Short answer
D 587
Question
Key Takeaways
Tests recognition of modern secure email ports versus legacy plaintext alternatives, with the common trap being the assumption that port 25 handles all secure email traffic.
Port 587 is the industry-standard port for secure email submission using TLS encryption. Community consensus strongly confirms it as the correct answer, distinguishing it from legacy unencrypted protocols.
Common mistake: Option A (Port 25) is frequently selected because it is historically tied to SMTP, but it lacks built-in encryption and is reserved for unsecured server-to-server relaying rather than client access.
Expert Analysis
Why the Answer Is Correct
Port 587 is officially designated for mail submission and mandates STARTTLS encryption by default, ensuring credentials and message content remain protected during transmission. CompTIA Network+ prioritizes this modern standard to reflect current cybersecurity best practices for endpoint-to-server communication.
Why the Other Options Are Wrong
Port 25 facilitates traditional SMTP routing but operates in plaintext, making it unsuitable for direct client connections. Port 110 represents legacy POP3, which transmits emails without encryption unless upgraded to the secure variant on port 995. Similarly, port 143 handles IMAP retrieval but lacks the inherent security provided by IMAPS on port 993.
Community Comment Notes
Examiners and users alike emphasize that port 587 leverages TLS encryption specifically for secure client submissions, clearly separating it from older protocols [1]. Multiple contributors clarify that while port 25 remains functional for infrastructure routing, it is definitively classified as insecure for modern usage [3]. The unanimous voting pattern demonstrates strong candidate alignment with official exam objectives regarding encrypted network services.
Official Reference
- https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml#service-names-port-numbers-1
- https://datatracker.ietf.org/doc/html/rfc6409
These links open the official vendor documentation in a new tab.
Exam Strategy
Always pair legacy ports with their secure equivalents when reviewing exam objectives (e.g., 587 replaces 25, 993 replaces 143, 995 replaces 110). If a question specifies 'secure,' 'TLS,' or 'client submission,' immediately discard plaintext options and select the encrypted counterpart.
Community Votes
100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 3 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 3
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Intel_Geek 👍 6 Answered DPort 25 is for SMTP, now considered insecure Port 110 is associated with POP3 which retrieves emails but is only secure with additional encryption Port 143 is associated with IMAP, without encryption Port 587 is the secure version of SMTP and uses TLS encryption
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chupapi_001 👍 4 Answered DThe correct answer is D: Port 587.
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HeatSquad77 👍 1 Answered DD. simple mail transfer protocol (SMTP) Application protocol used to send mail between hosts on the Internet. Messages are sent between servers over TCP port 25 or submitted by a mail client over secure port TCP/587.
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