A user sends an email from Gmail to a Yahoo address. Which protocol transfers the message from Gmail's mail server to Yahoo's mail server?
AIMAP, because Yahoo's server needs to retrieve the message from Gmail
BSMTP, because mail transmission between servers uses SMTP
CPOP3, because POP3 handles server-to-server message transfer
DDNS alone, because the MX record lookup delivers the message directly
SMTP handles all mail transmission — from client to server and between mail servers. Gmail's SMTP server looks up Yahoo's MX record via DNS, then opens a TCP connection to Yahoo's SMTP server and pushes the message. DNS resolves the destination address but does not deliver the message. IMAP and POP3 are only for clients retrieving messages from their own mail server.
Question 2 Multiple Choice
A user configures their laptop with POP3, reads several emails, then checks the same account on their phone. The previously-read emails are absent from the phone. What explains this?
AThis is a server error; both devices should always see the same messages
BThis is expected POP3 behavior: messages were downloaded to the laptop and deleted from the server, so the phone has nothing to retrieve
CIMAP was misconfigured on the phone, preventing synchronization
DThe emails were automatically archived by the server after 24 hours
POP3's default behavior is to download messages to the client and delete them from the server. Once the laptop downloaded the messages, they were removed — leaving nothing for the phone to retrieve. This 'download and delete' model was designed for single-device access. IMAP keeps messages on the server so all devices always see the same mailbox state.
Question 3 True / False
SMTP can be used to retrieve email from a mail server, just as IMAP and POP3 can.
TTrue
FFalse
Answer: False
SMTP is a push-only sending protocol — it moves email from client to server and between mail servers. It cannot retrieve messages. Retrieval always requires POP3 or IMAP. This separation of concerns is fundamental to email architecture: sending and receiving use entirely different protocols operating on different TCP ports.
Question 4 True / False
An email client using IMAP stores the authoritative copy of messages on the local device, synchronizing back to the server.
TTrue
FFalse
Answer: False
IMAP treats the server as the primary storage location. Messages remain on the server; the client views and manipulates them remotely. Any action — reading, deleting, organizing into folders — is recorded on the server and reflected across all devices. This is the opposite of POP3, where the downloaded local copy becomes the only copy once it's removed from the server.
Question 5 Short Answer
Explain why someone who accesses email from multiple devices (phone, laptop, tablet) should prefer IMAP over POP3.
Think about your answer, then reveal below.
Model answer: IMAP stores messages on the server and synchronizes state (read/unread status, flags, folders) across all devices. Any action on one device is immediately reflected on all others. POP3 downloads messages to a single device and deletes them from the server by default, so other devices lose access to those messages and see no synchronized state.
The fundamental difference is where the master copy lives. POP3 was designed when people used a single desktop computer for email. IMAP was designed for multi-device access — the server is the source of truth, and every client is a synchronized view of that server state.