220-1102 Question 340
Single answerEmailA user reports that they can send email from their company laptop while connected to the office network, but when working remotely from home, outgoing messages stay in the Outbox and eventually fail. They can still receive new email without any issues. The email account is configured manually in a desktop mail client. Which setting is the MOST likely causing the problem?
- A
The outgoing mail server is set to SMTP on port 25 with no authentication
- B
The incoming mail server is configured as IMAP instead of POP3
- C
The mailbox quota has been exceeded on the server
- D
The DNS server address on the laptop is set manually instead of obtained automatically
Show answer and explanation
Correct answer: A
Explanation
This scenario tests practical troubleshooting of email client configuration. Sending and receiving use different protocols: SMTP is used for outgoing mail, while IMAP or POP3 is used for incoming mail. A common real-world issue is that a manually configured client uses legacy SMTP settings such as port 25 and no authentication. That may work on a corporate LAN with an internal mail relay but fail on external networks because port 25 is commonly restricted by ISPs and many providers require authenticated message submission. Current best practice is to use SMTP submission with authentication, typically on port 587 with STARTTLS, or port 465 if the provider supports implicit TLS. This aligns with common vendor documentation from Microsoft, Google, and other mail providers, which recommend authenticated encrypted SMTP submission rather than unauthenticated port 25 for client devices.
- A. Correct.
Correct. SMTP is used for sending mail, and many ISPs and remote networks block outbound traffic on TCP port 25 to reduce spam. In addition, modern mail systems typically require authenticated SMTP submission, usually on port 587 with STARTTLS or port 465 with implicit TLS. If the client is configured to use port 25 without authentication, it may work only on the internal office network but fail from home.
- B. Incorrect.
Incorrect. IMAP versus POP3 affects how incoming mail is retrieved and synchronized, not whether outgoing mail can be sent. Since the user can still receive email, the incoming protocol is not the most likely cause of the sending failure.
- C. Incorrect.
Incorrect. A full mailbox can prevent receiving additional messages and, depending on the provider, may affect sending in some environments. However, the scenario specifically indicates that the user can still receive email and that the issue occurs only when working remotely, which points more directly to an SMTP configuration problem rather than quota.
- D. Incorrect.
Incorrect. A DNS misconfiguration could cause broader connectivity problems, such as inability to resolve mail server names for both sending and receiving. Because the user is successfully receiving email, DNS is less likely to be the specific root cause. The location-dependent nature of the issue is more consistent with blocked or improperly configured SMTP submission.