Question 386 of 972
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220-1201 Practice Question: That they cannot send emails from their Outlook…
A user reports that they cannot send emails from their Outlook client, but they can receive emails. The email server is using standard ports. Which port is most likely blocked on the firewall?
⚠ Common exam trap
This question tests the distinction between incoming and outgoing mail ports. The trap is that candidates confuse port 110 or 143 (both for receiving) with the sending port, or assume port 443 is used for email because of its association with secure web traffic.
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
✓
25
Port 25 is the default SMTP port used for outgoing email transmission. If a firewall blocks port 25, the Outlook client cannot connect to the SMTP server to send emails, but receiving via POP3 (port 110) or IMAP (port 143) remains unaffected. This matches the user's symptom of being able to receive but not send emails.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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110
Why it's wrong here
Port 110 is exclusively designated for the Post Office Protocol version 3 (POP3). POP3 is an email retrieval protocol that downloads messages from a mail server to a local client, typically deleting them from the server afterward. If port 110 were blocked, a user would be unable to *receive* emails via POP3, but their ability to *send* emails would remain unaffected, as sending uses a different protocol and port.
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143
Why it's wrong here
Port 143 is the standard port for the Internet Message Access Protocol (IMAP). IMAP is an email retrieval protocol that allows users to access and manage their emails directly on the mail server, synchronizing changes across multiple devices. While a block on port 143 would prevent a user from *accessing or receiving* emails via IMAP, it has no bearing on the outgoing email process, which relies on a separate sending protocol.
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25
Why this is correct
Port 25 is the default port for the Simple Mail Transfer Protocol (SMTP), which is the industry standard for sending email messages between mail servers and from a mail client to a mail server. If port 25 is blocked, the email client or server would be unable to establish a connection to an outgoing mail server, directly preventing the user from sending emails. This aligns precisely with the user's reported inability to send.
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443
Why it's wrong here
Port 443 is primarily used for HTTPS (Hypertext Transfer Protocol Secure), which provides encrypted communication over a computer network, most commonly for secure web browsing. While some webmail interfaces might use HTTPS for accessing the web-based client, blocking port 443 would primarily impact secure website access, not the underlying protocol used by dedicated email clients to send messages. It is unrelated to the SMTP process.
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Last reviewed: Jul 4, 2026
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.
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