When you add your email to a phone or mail app, it asks you to choose IMAP or POP3. The short answer to IMAP vs POP3: pick IMAP unless you have a specific reason not to. This article explains the difference, when POP3 still makes sense, and how to switch without losing mail.
The difference between IMAP and POP3
IMAP: your mail lives on the server
With IMAP, your messages and folders stay on our mail server. Your apps show a synced view of them. Read a message on your phone and it shows as read on your laptop. Move it to a folder in webmail and it moves everywhere. Sent mail and drafts can be shared across devices too.
POP3: your mail is downloaded to one device
With POP3, your mail app downloads new messages from the Inbox and, by default in many apps, deletes them from the server afterwards. The copy on that computer becomes the only copy. Folders, sent items and read status are not synced. Other devices and webmail won't see those messages.
Quick comparison
| IMAP | POP3 | |
|---|---|---|
| Where mail is stored | On the server | On your device (usually) |
| Works on several devices | Yes, everything stays in sync | Not well -- each device gets its own copy, or none |
| Folders and sent mail synced | Yes | No, Inbox only |
| Uses your mailbox quota | Yes, all stored mail counts | Only what is left on the server |
| Included in the Instant Access Internet Services server backups | Yes | Only mail still on the server |
| Secure port | 993 (SSL/TLS) | 995 (SSL/TLS) |
Sending mail works the same either way: both use SMTP on port 465 (SSL/TLS) or 587 (STARTTLS). See Email Server Settings and Ports (IMAP, POP3 and SMTP) for the full list of settings.
Which should you use?
Choose IMAP if...
- You check email on more than one device (almost everyone does).
- You want to use webmail as well as a mail app.
- You want your mail protected by our server backups if your computer dies or a phone is lost.
- More than one person reads the same mailbox.
POP3 can make sense if...
- You only ever read mail on one computer, and you back that computer up yourself.
- You get large volumes of mail and want to keep the server mailbox small.
If you use POP3, turn on the app's option to leave messages on the server (the wording varies), at least for a while, so a failed download doesn't lose mail.
What about storage space?
Because IMAP keeps everything on the server, the mailbox slowly fills up. That's the main downside. You can raise the quota or clean out old mail -- see How to Change an Email Account's Storage Quota in cPanel and How to Free Up Mailbox Space with Email Disk Usage. If a mailbox fills completely, new mail bounces; How to Fix "Mailbox Full" Errors explains how to fix it.
How to switch from POP3 to IMAP
Most apps won't let you change an existing account from POP3 to IMAP. Instead you add the account again as IMAP:
- First, make sure you have a copy of any mail that exists only in the POP3 app (it may be the only copy).
- Add the same email address to the app again, choosing IMAP with the settings from How to Find Your Email Settings with Connect Devices.
- If you want your old downloaded mail on the server, drag the messages from the POP3 account's folders into the IMAP account's folders. They will upload to the server and appear on every device.
- When everything is copied, remove the old POP3 account from the app.
Uploading a large archive this way can push the mailbox over its quota, so check the quota first.
Common questions
Why did my emails disappear from webmail?
A device set up with POP3 probably downloaded them and removed them from the server. Check each of your devices; the messages should be on the one using POP3. Switch that device to IMAP to stop it happening again.
Does IMAP sync my calendar and contacts too?
No. IMAP and POP3 only handle email. Calendars and contacts sync separately using CalDAV and CardDAV -- see How to Sync Calendars and Contacts (CalDAV and CardDAV).
Related guides
- Email Server Settings and Ports (IMAP, POP3 and SMTP)
- How to Find Your Email Settings with Connect Devices
- How to Free Up Mailbox Space with Email Disk Usage
- How to Move Your Email from Another Host
Still stuck? Open a support ticket and the Instant Access Internet Services team will help.
