Use IMAP for almost every situation. IMAP keeps your email on the server and syncs it across all your devices, so your phone, laptop and webmail show the same inbox, folders and read status. POP3 downloads mail to one device and usually removes it from the server, which was sensible when mailboxes were tiny and everyone had one computer, but causes lost and scattered mail today.
Here is how each protocol works, when POP3 still makes sense, and the exact settings to use.
How IMAP works
IMAP (Internet Message Access Protocol) treats the server as the master copy of your mailbox. Your mail app shows what is on the server and keeps a local copy for speed.
- Read a message on your phone and it shows as read on your laptop.
- Move a message into a folder and the folder is updated everywhere.
- Sent items and drafts can be saved on the server, so every device sees them.
- Lose or replace a device and nothing is lost, because the mail is still on the server.
How POP3 works
POP3 (Post Office Protocol version 3) is simpler. Your mail app connects, downloads new messages and, by default, deletes them from the server.
- Mail lives on the one device that downloaded it.
- Folders, read status and sent items are local to that device.
- If that device fails and has no backup, the mail is gone.
- You can set "leave a copy on the server", but read status and folders still do not sync.
IMAP vs POP3 side by side
| IMAP | POP3 | |
|---|---|---|
| Where mail is stored | On the server (with a local cache) | On the device that downloads it |
| Multiple devices | Fully synced | Not synced |
| Folders | Synced to the server | Local only |
| Sent items | Can be stored on the server | Local only |
| Offline access | Yes, for cached messages | Yes, for everything downloaded |
| Server storage used | More, mail stays on the server | Less, if mail is deleted after download |
| Device loss | No mail lost | Mail lost unless backed up |
| Best for | Nearly everyone | One device, archiving to local storage |
When POP3 still makes sense
POP3 is not wrong, just specialised. It can suit you if:
- You only ever read mail on one computer, and that computer is backed up properly.
- Your mailbox quota is small and you need to keep years of mail locally.
- You deliberately want an offline archive that is not stored on the server.
Even then, many people are better served by IMAP plus an archive: keep recent mail on the server and archive older mail to a local or backed-up folder.
Correct ports and security settings
Always use encrypted connections. These are the standard ports:
| Protocol | Port | Security |
|---|---|---|
| IMAP | 993 | SSL/TLS |
| IMAP | 143 | STARTTLS (only if 993 is not offered) |
| POP3 | 995 | SSL/TLS |
| POP3 | 110 | STARTTLS (only if 995 is not offered) |
| SMTP submission (sending) | 587 | STARTTLS |
| SMTP submission (sending) | 465 | SSL/TLS |
Outgoing mail always uses SMTP, whichever protocol you choose for incoming mail. Turn on SMTP authentication with the same username and password as your mailbox. Avoid port 25 for sending from mail apps; it is meant for server-to-server delivery and many networks block it.
The server names come from your email provider. For a full walkthrough of adding an account to Outlook, iPhone and Android, see how to set up email on your own domain.
How to switch from POP3 to IMAP without losing mail
If you have been using POP3, some of your mail probably exists only on your computer. Switch carefully:
- Back up your current mail app's data (for example export to a PST file in Outlook).
- Add the same mailbox again as an IMAP account. Do not delete the POP3 account yet.
- Copy the messages you want to keep from the POP3 folders into the IMAP inbox or folders. They upload to the server.
- Check mailbox quota. Uploading years of mail may need a larger mailbox, or you can keep older mail in a local archive.
- Check on another device that the uploaded mail appears.
- Remove the POP3 account once everything is on the server.
Moving to a new email host at the same time? Follow how to migrate email to a new host, which covers copying mailboxes server to server.
What about Exchange and other protocols?
Microsoft Exchange (including Microsoft 365) and Google Workspace also offer their own sync methods that go beyond IMAP, for example syncing calendars and contacts. If you use one of those services, their own apps or Exchange/ActiveSync connections usually give the best experience. For standard email hosting, IMAP is the right choice. We compare the options in email hosting vs Google Workspace vs Microsoft 365.
Frequently asked questions
Is IMAP or POP3 more secure?
Neither is inherently more secure; what matters is using an encrypted connection (IMAP on 993 or POP3 on 995), a strong unique password and a trustworthy provider. IMAP does mean your mail stays on the server, so choose a provider that protects and backs it up.
Does IMAP use more mailbox storage?
Yes, because mail stays on the server. Archive or delete old messages and large attachments regularly, or choose a larger mailbox if you need to keep everything.
Can I use IMAP on my phone and POP3 on my computer?
You can, but it causes confusion. If the computer's POP3 client deletes messages from the server, they disappear from your phone. Use IMAP everywhere.
Why do my sent items not show on my phone?
Your mail app is saving sent mail locally instead of to the server's Sent folder. With IMAP, set the app to store sent messages in the server's Sent folder.
Do I need to change anything on the server to use IMAP?
Usually not. Most email hosting supports both IMAP and POP3; you simply choose IMAP when adding the account in your mail app.
Looking for business email that syncs properly across every device? NewHost email hosting gives you IMAP mailboxes on your own domain, with local support to help you connect your phone and computer.