IMAP and POP3 are both protocols for retrieving email from a mail server to your email client. They do the same job in fundamentally different ways, and that difference matters a lot when you're working across multiple devices. For almost every business use case, the answer is IMAP, but understanding why helps you configure your email correctly and troubleshoot when things go wrong.
IMAP (Internet Message Access Protocol) keeps your email on the server. Your email client synchronises with the server, showing you the current state of your mailbox. When you read, move, delete, or star a message, that change is recorded on the server and immediately reflected on all other devices connected to the same account.
This is why reading an email on your phone marks it as read in Outlook on your desktop. The email lives on the server; your clients are just views into the same data. IMAP was designed for exactly this use case, multiple clients accessing the same mailbox, and it handles it well. The standard IMAP port is 993 (SSL/TLS) or 143 (STARTTLS).
POP3 (Post Office Protocol version 3) downloads email from the server to your client and, by default, deletes it from the server. The metaphor is a physical post office: you collect your letters, they're no longer at the post office. Once downloaded, the email only exists on the device that retrieved it.
POP3 does have an option to leave copies on the server (configurable in most clients), but even then, the protocol has no mechanism to synchronise read/unread status, folder structure, or deletions between devices. Each device maintains its own independent copy. The standard POP3 port is 995 (SSL/TLS) or 110 (unencrypted, never use this).
Modern business email is accessed from at least two places: a desktop computer and a smartphone. Many people also use webmail occasionally. IMAP keeps all three in sync automatically. POP3 doesn't, if your phone downloads a message first and your desktop hasn't synced yet, the message may only exist on your phone.
IMAP also makes backup and recovery straightforward. Since email stays on the server, your hosting provider's backup systems protect your mail. With POP3 and local-only storage, a failed hard drive means lost email. For a business, that's an unacceptable risk without a separate local backup strategy.
POP3 has a legitimate use case when mailbox storage is severely limited and you access email from only one device. Some hosting plans offer small mailboxes (1–5 GB), and if you receive a lot of attachments, storage fills quickly. Using POP3 with deletion keeps your server mailbox empty, deferring the storage burden to your local machine.
It also makes sense for archiving: some businesses use a POP3 connection specifically to pull all email into a local archiving system (like a legal or compliance archive) while keeping the primary access via IMAP. In that specific setup, POP3 is used as a download-only pipe, not as the primary email protocol.
IMAP and POP3 handle incoming mail only. Sending email is handled by SMTP (Simple Mail Transfer Protocol) regardless of which incoming protocol you use. This is a source of frequent confusion when configuring email clients, you always need both an incoming server (IMAP or POP3) and an outgoing server (SMTP) configured separately.
Standard SMTP settings: port 587 with STARTTLS (preferred) or port 465 with SSL. Port 25 is the traditional SMTP port but is blocked by most hosting providers for security reasons, don't use it. Authentication is required on ports 587 and 465, using your full email address and password.
Apple Mail (iOS / macOS): Settings > Mail > Add Account > Other. Enter your email address, then manually enter the IMAP settings from your hosting provider. Select SSL, port 993 for incoming. For outgoing, port 587 with TLS or 465 with SSL.
Microsoft Outlook: File > Add Account > Manual Setup. Select IMAP. Enter your name, email address, incoming server address, and outgoing SMTP server. Under More Settings > Outgoing Server, check "My outgoing server requires authentication." Under Advanced, set incoming port to 993 (SSL) and outgoing to 587 (TLS) or 465 (SSL).
Mozilla Thunderbird: Thunderbird usually auto-detects IMAP settings if your provider follows standard configurations. If not, use Account Settings > Server Settings to manually enter the incoming server details, and Account Settings > Outgoing Server (SMTP) for the outgoing configuration.
If you use Google Workspace or Microsoft 365, you may not need to configure IMAP or POP3 at all. Both platforms support Microsoft Exchange ActiveSync (or native protocols), which provides even better synchronisation than IMAP, including contacts, calendar, and tasks, not just email. iPhone and Android both support Exchange natively, and setting it up is simpler than configuring manual IMAP.
For hosting-provider email (cPanel/Plesk), IMAP is the standard. Exchange is only available through Microsoft 365 or hosted Exchange services. If your email is hosted on a standard cPanel server, IMAP is your best option and is well supported across all major email clients.
HostBible hosting plans include email with IMAP, POP3, and SMTP access, configure any email client on any device and stay in sync.
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