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220-1201 Practice Question: That they can send emails but cannot receive any
A user reports that they can send emails but cannot receive any. The email client is configured with SMTP for outgoing and POP3 for incoming. The server is reachable. Which port is most likely blocked on the firewall for the incoming mail protocol?
⚠ Common exam trap
CompTIA often tests the distinction between SMTP (port 25) and POP3 (port 110) by describing a scenario where only one direction of email flow is broken, leading candidates to mistakenly focus on the outgoing port.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Port 110
The user can send emails (SMTP works) but cannot receive them, and the incoming protocol is POP3. POP3 uses port 110 by default. Since the server is reachable, a firewall blocking port 110 would prevent the email client from retrieving incoming messages, while SMTP on port 25 remains unaffected.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Port 25
Why it's wrong here
Port 25 is SMTP, used for sending; if sending works, this port is open.
- ✓
Port 110
Why this is correct
Port 110 is the default port for POP3, used for receiving email; if blocked, incoming mail fails.
- ✗
Port 443
Why it's wrong here
Port 443 is HTTPS, used for secure web traffic, not for email receiving.
- ✗
Port 53
Why it's wrong here
Port 53 is DNS, used for name resolution, not for email.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1201 exam.