250STARTTLS

250STARTTLS is a command used in the Simple Mail Transfer Protocol (SMTP) to initiate a secure connection between an email client and a mail server. It is part of the STARTTLS extension, which allows the use of Transport Layer Security (TLS) to encrypt the communication between the client and the server. The command is typically issued by the client after establishing an initial connection to the server. Upon receiving the 250STARTTLS command, the server responds with a 220 Ready to start TLS command, indicating that it is ready to begin the TLS handshake. This process ensures that the email data transmitted between the client and the server is encrypted, protecting it from eavesdropping and tampering. The use of 250STARTTLS is widely supported and recommended for securing email communications.