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Email Protocols

IMAP(Internet Message Access Protocol)

A protocol for retrieving and managing email messages stored on a mail server.

Definition

IMAP (Internet Message Access Protocol) is a standard protocol that allows email clients to access and manage messages stored on a remote mail server. Unlike POP3, which downloads emails to your device, IMAP keeps messages on the server and syncs across all your devices. This means you can read an email on your phone and see it marked as read on your computer. IMAP was designed for the modern multi-device world where users access email from phones, tablets, laptops, and web browsers.

Why It Matters

For email marketers, IMAP matters when setting up shared inboxes for support or sales teams. It also affects how recipients interact with your emails. Since IMAP syncs read status across devices, your open tracking may be more accurate as users typically only trigger the tracking pixel once. Understanding IMAP helps when troubleshooting why customers say they did not receive emails - they may be looking in the wrong folder or device.

How It Works

IMAP maintains a persistent connection to the mail server, allowing real-time synchronization. When you open your email client, it fetches message headers first for quick display, then downloads full messages as needed. Actions like reading, deleting, or moving emails are synced back to the server immediately. IMAP supports folder hierarchies, search on the server, and partial message fetching for efficiency.

Example

Imagine you are on a sales call and check your email on your phone. You see a prospect's reply and mark it as important.

Later at your desk, you open Outlook and that same email already shows as important with the star you added. You reply from your laptop.

That night on your tablet, you see the full conversation thread including your reply. This seamless experience across three devices is possible because IMAP keeps everything synchronized on the mail server.

Best Practices

  • 1Use IMAP for shared team inboxes to maintain sync across team members
  • 2Configure proper folder structures for organizing customer communications
  • 3Set up appropriate retention policies on the server to manage storage
  • 4Use IMAP with TLS encryption (port 993) for security
  • 5Regularly clean up old emails to keep server storage manageable

Frequently Asked Questions

Use IMAP if you check email on multiple devices and want messages synced everywhere. Use POP3 only if you need to download emails locally and remove them from the server, which is rare today. IMAP is the standard for modern email usage.

IMAP can cache emails locally for offline access, but the primary storage remains on the server. This means your emails are safe even if your device is lost or damaged. The local cache is just for convenience and speed.

IMAP uses port 143 for standard connections and port 993 for secure connections with TLS/SSL encryption. Always use port 993 with encryption for security. Never use unencrypted IMAP as your credentials could be intercepted.