Need of STARTTLS and DANE SMTP Extensions
- Initially, when the Simple Mail Transport Protocol(SMTP) was adopted, all the messages were communicated as plain text. No encryption methods and algorithms were applied to the message data.
- Any unauthorized person trying to steal or check for the content was able to read the actual data that was transmitted between two servers.
- Later on, Extend SMTP (ESMTP) made it possible to transmit the encrypted data rather than sending simple plain text.
- Encryption was not mandatory for all the servers because all the servers were not able to handle transport encryption.
- In order to indicate the ability of encryption to the sending server, it was made mandatory that the receiving server needs to send the keyword STARTTLS at the beginning of an ESMTP transport session.
SMTP Extensions: STARTTLS, and DANE
SMTP stands for Simple Mail Transfer Protocol. SMTP is an application layer protocol. Whenever a client needs to send mail, opens a TCP connection to the SMTP server and then sends mail over the network. The connection is established by the SMTP server through port 25.