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# What is IMAP?

| What is IMAP?
---

**IMAP**, especially the current version (**IMAP4**), is a more sophisticated protocol.

It allows users to group related messages and place them in folders, which can in turn be arranged hierarchically.

It's also equipped with message flags that indicate whether a message has been read, deleted, or replied to.

It even allows users to carry out searches against the server mailboxes.

Here's how **IMAP** works in a nutshell:

* Connects to the mail server on port 143 (or 993 for SSL/TLS connections);
* Retrieves email messages;
* Stays connected until the mail client app is closed and downloads messages on demand.
* Notice that messages aren't deleted on the server. This has major implications, which we'll talk about shortly.

**IMAP** specifications can be found in **RFC 3501**.