IMAP is short for Internet Message Access Protocol. The IMAP is an internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. IMAP is defined by RFC 3501.

As its name implies, IMAP allows you to access email messages wherever you are. Much of the time, it is accessed via the internet.

Email messages are stored on servers. Whenever you check your inbox, your email client contacts the server to connect you with your messages. When you read an email message using IMAP, you aren’t actually downloading or storing it on your computer. Instead, you are reading it off of the server. As a result, it’s possible to check your email from several different devices without missing a thing.

The easiest way to understand how IMAP works is by thinking of it as an intermediary between your email client (which can be cloudHQ) and your email server (e.g. Google Gmail). Email servers are always used when sending and receiving email messages. With IMAP, though, they remain on the server unless you explicitly delete them. When you sign into an email client like Microsoft Outlook, it contacts the email server using IMAP. The headers of all of your email messages are then displayed. If you choose to read a message, it is quickly downloaded so that you can see it. Emails are not downloaded unless you need to open them.

IMAP was designed with the goal of permitting complete management of an email inbox by multiple email clients, therefore clients generally leave messages on the server until the user explicitly deletes them. An IMAP server typically listens on port number 143. IMAP over SSL (IMAPS) is assigned the port number 993.

Virtually all modern email clients and servers support IMAP. IMAP and the earlier POP3 (Post Office Protocol) are the two most prevalent standard protocols for email retrieval, with many webmail service providers such as Gmail, and Yahoo! Mail also providing support for IMAP.