Every time you open your email client — whether it's Outlook, Thunderbird, or the Mail app on your phone — it connects to the mail server using either IMAP or POP3. Both protocols do the same basic job (fetching your messages), but they work in fundamentally different ways. Understanding these differences helps you pick the right setup for your workflow.
What are IMAP and POP3?
IMAP (Internet Message Access Protocol) keeps your emails stored on the mail server and synchronises them across every device you use. When you read, delete, or organise a message on one device, that change appears everywhere. Your mailbox lives on the server, and your email client simply displays a mirror of it.
POP3 (Post Office Protocol version 3) downloads your emails from the server to a single device. Once downloaded, the messages typically exist only on that device. By default, POP3 removes emails from the server after downloading them, although most clients let you override this behaviour.
Key differences
The core distinction is simple: IMAP syncs, POP3 downloads. This single difference has several practical consequences:
- Multi-device access — IMAP lets you check email from your laptop, phone, and tablet with everything in sync. POP3 ties your messages to one device.
- Server storage — IMAP uses server storage because emails remain on the server. POP3 frees up server space by moving messages to your local device.
- Offline access — POP3 emails are always available offline since they are stored locally. IMAP requires an internet connection to load messages (though most clients cache recent emails).
- Backup safety — With IMAP, your emails are backed up on the server. With POP3, if your device fails and you have no local backup, your emails are gone.
Comparison table
| Feature | IMAP | POP3 |
|---|---|---|
| Email storage | On the server | On your device |
| Multi-device sync | Yes — all devices stay in sync | No — each device is independent |
| Offline access | Limited (cached emails only) | Full — all downloaded emails available |
| Server space usage | Higher — emails remain on server | Lower — emails removed after download |
| Backup | Server-side (automatic daily backups at HOSTDOG) | Your responsibility (local backups) |
| SSL port | 993 |
995 |
| Best for | Most users, multiple devices | Single device, limited server storage |
When to use IMAP
IMAP is the right choice for the vast majority of users. Choose IMAP if you:
- Check email on more than one device (phone, laptop, tablet)
- Want read/unread status, folders, and drafts to stay consistent everywhere
- Prefer server-side backups so your email survives a device failure
- Use webmail alongside a desktop or mobile client
HOSTDOG Business Hosting plans include unlimited mailbox storage, making IMAP an ideal fit since server space is not a concern. Personal Hosting plans offer up to 1 GB per mailbox, which is sufficient for most users who manage their inbox regularly.
When to use POP3
POP3 can still be useful in specific situations. Consider POP3 if you:
- Only use one device to read email
- Need to free up server storage on a plan with limited mailbox space
- Want full offline access to your entire email archive
- Prefer to keep all messages stored locally for privacy reasons
HOSTDOG recommendation
We recommend IMAP for all HOSTDOG customers. It provides the most flexible and reliable email experience, especially when combined with our daily server backups. Whether you are on a Personal or Business plan, IMAP ensures your messages are always accessible and protected.
For the server settings you need to configure IMAP or POP3, see HOSTDOG email server settings.
Frequently asked questions
Yes. Create a new IMAP account in your email client alongside the existing POP3 account, then drag your emails from the POP3 folders to the IMAP folders. Once everything is copied, you can remove the POP3 account.
Yes, because IMAP keeps all emails on the server. On HOSTDOG Business plans this is not an issue since mailbox storage is unlimited. On Personal plans (up to 1 GB per mailbox), periodically archive or delete old messages to keep usage in check.
IMAP uses port 993 with SSL/TLS encryption. POP3 uses port 995 with SSL/TLS encryption. For outgoing email (SMTP), use port 465 (SSL) or 587 (STARTTLS). See our email server settings page for full details.
Technically yes — you could set up IMAP on your phone and POP3 on your desktop. However, this is not recommended as it creates inconsistencies between devices. For the best experience, use IMAP on all your devices.