IMAPS (Internet Message Access Protocol over SSL/TLS) is a secure variant of IMAP that utilizes SSL/TLS encryption to protect the communication between email clients and servers. Here’s a brief history of IMAPS:

1. Introduction of SSL/TLS: In the mid-1990s, SSL (Secure Sockets Layer) was developed by Netscape Communications as a security protocol for encrypted communication over the internet. SSL provided authentication and encryption to protect data transmitted between clients and servers.
2. SSL/TLS with IMAP: To secure IMAP communication, SSL/TLS was integrated with the protocol, resulting in IMAP over SSL/TLS, commonly referred to as IMAPS. IMAPS allows for the encryption of the entire IMAP session, ensuring the confidentiality and integrity of email retrieval and management.
3. Transition from SSL to TLS: SSL was eventually succeeded by TLS (Transport Layer Security) as the standardized security protocol. Although the term “IMAPS” still persists, it typically refers to the usage of TLS rather than SSL.
4. Operation of IMAPS: IMAPS operates similarly to IMAP, but with the added layer of SSL/TLS encryption. The client establishes a secure connection with the IMAPS server using SSL/TLS, encrypting the communication between the client and server. The standard port for IMAPS is usually 993.
5. Popularity of STARTTLS: Over time, an alternative approach called STARTTLS gained popularity for securing IMAP communication. STARTTLS allows for the negotiation of a secure TLS connection within the standard IMAP protocol, eliminating the need for a separate port like in the case of IMAPS.

As a result of the industry’s shift towards STARTTLS, the usage of IMAPS has become less common. Many email clients and servers now prioritize STARTTLS as the preferred method for securing IMAP communication. It offers greater flexibility and compatibility since it can work on the same port as non-encrypted IMAP, allowing for seamless transitioning between encrypted and non-encrypted connections.