Port 993 is used for secure IMAP (Internet Message Access Protocol) connections. IMAP allows email clients to access email messages stored on a mail server. Port 993 specifically designates IMAP over SSL/TLS (IMAPS), which encrypts the communication between the email client and the server, ensuring data confidentiality and integrity during transmission.
Port 993 and port 995 both serve secure email protocols, but they differ in their specific applications. Port 993 is used for IMAP over SSL/TLS (IMAPS), while port 995 is used for POP3 over SSL/TLS (POP3S). IMAP and POP3 are different email retrieval protocols, with IMAP offering more features for managing emails on the server, whereas POP3 typically downloads emails to the client device.
Port 993 is typically used for inbound connections. In networking terminology, inbound and outbound refer to the direction of network traffic relative to a device or network. For port 993, inbound traffic refers to connections initiated from external sources (like email clients) towards the server hosting the IMAP service. This allows clients to securely retrieve email messages from the server over the encrypted IMAP protocol.
Port 993 is considered secure because it uses SSL/TLS encryption to protect the communication between the email client and the server. SSL/TLS (Secure Sockets Layer/Transport Layer Security) protocols encrypt data transmitted over the network, preventing unauthorized interception and ensuring the confidentiality and integrity of email communications.
The incoming port for SSL depends on the specific application or service utilizing SSL/TLS encryption. For example, for secure email protocols like IMAPS (IMAP over SSL/TLS), the incoming port is typically port 993. Similarly, for other SSL/TLS-secured services like HTTPS (secure web browsing), the incoming port is usually port 443. The specific port number used depends on the application’s configuration and the network protocol being secured with SSL/TLS encryption.