POP3 vs IMAP (reading email)
Both protocols fetch mail from a server, but they treat your inbox completely differently. Here’s how each works and which one you actually want.
The job they share
SMTP moves mail to a server. POP3 and IMAP move it from the server to your mail client so you can read it. They are retrieval protocols, and the difference between them comes down to one question: where do your messages actually live?
POP3, download and (usually) delete
The Post Office Protocol (POP3, port 110 / 995 for TLS) was designed for one device on an intermittent connection. The client connects, downloads new messages to local storage, and by default removes them from the server. Mail then lives on that one device. It’s simple and storage-light on the server, but it predates the idea that you’d check the same inbox from a phone, a laptop, and a browser.
IMAP, the server is the source of truth
The Internet Message Access Protocol (IMAP, port 143 / 993 for TLS) keeps messages on the server and lets clients view and manipulate them in place. Folders, read/unread state, flags, and deletions all sync back to the server, so every device sees the same inbox. Clients typically cache messages locally for speed and offline reading, but the server holds the canonical copy.
Head to head
- Where mail lives: POP3, on your device. IMAP, on the server.
- Multiple devices: POP3, messy and out of sync. IMAP, consistent everywhere.
- Server storage: POP3, minimal. IMAP, you need enough quota to hold everything.
- Offline access: POP3, full, it’s all local. IMAP, whatever the client has cached.
- Folders & state sync: POP3, none. IMAP, yes.
Which should you use?
For almost everyone today, IMAP: you check mail from more than one device and expect a consistent inbox. Reach for POP3 only in narrow cases: a single device, a deliberate desire to pull mail off the server entirely, or a strict local-archive workflow. (Most modern providers also offer proprietary sync APIs, but IMAP remains the open standard.)
FAQ
Does POP3 always delete from the server?
No, most clients offer a “leave a copy on the server” option. But it’s still single-device thinking; state isn’t synced back the way IMAP does it.
Do POP3/IMAP send mail?
No. They only retrieve. Sending always goes through SMTP, which is why mail clients ask you to configure both an incoming and an outgoing server.
Are they encrypted?
Use the TLS ports, 995 for POP3 and 993 for IMAP, so credentials and messages aren’t sent in the clear.
Related
Sending mail is SMTP. See the full Reference for more protocol explainers.