mediumMultiple Choice
220-1201 Practice Question: That they can receive emails but cannot send any
A user reports that they can receive emails but cannot send any. The email client is configured with SMTP on port 25. The IT team confirms that port 25 is blocked by the ISP. Which alternative port should be used for SMTP submission?
⚠ Common exam trap
CompTIA often tests the misconception that any port associated with email (like POP3 on 110 or IMAP on 143) can be used for sending, when in fact only SMTP-specific ports (25, 587, or 465) handle outgoing mail.
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 587
Port 587 is the standard SMTP submission port defined in RFC 6409 for email clients to send outgoing mail. Unlike port 25, which is used for SMTP relay between mail servers and is often blocked by ISPs to prevent spam, port 587 is specifically designated for client-to-server submission and typically supports STARTTLS encryption. Using port 587 bypasses the ISP's block on port 25 while adhering to modern email security practices.
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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Port 110
Why it's wrong here
Port 110 serves POP3 mailbox retrieval, not message submission, so the client still cannot send. POP3 is tempting because it is a familiar mail protocol, but it only downloads mail; SMTP submission belongs on port 587 (or 465).
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Port 143
Why it's wrong here
Port 143 carries unencrypted IMAP for mailbox access, not outbound message submission. IMAP is tempting because it is a standard email protocol, but it retrieves mail; SMTP submission must use port 587 or 465 instead.
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Port 587
Why this is correct
Port 587 is the standard SMTP submission port, used by mail clients to authenticate and send outgoing messages. Since the ISP blocks port 25, switching the client's SMTP configuration to 587 restores sending while receiving via IMAP or POP3 remains unaffected.
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Port 993
Why it's wrong here
Port 993 carries IMAP over TLS for retrieving mailbox contents, not submitting outgoing mail. IMAP is tempting since it is a core mail protocol, but it handles inbound synchronisation only; SMTP submission requires port 587 or 465.
Go deeper
Related to this question
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Key term
SMTP
SMTP (Simple Mail Transfer Protocol) is the standard internet protocol used to send emails from a client to a server or between email servers.
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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.