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STARTTLS

STARTTLS is an SMTP command used to initiate a secure connection over the Transport Layer Security (TLS) protocol^[600-developer-smtp.md]. It allows the communication channel between a Mail User Agent (MUA) or Mail Transfer Agent (MTA) and the server to be encrypted^[600-developer-smtp.md].

Mechanism

The command is issued after the client initiates the session using the EHLO (Extended SMTP) command^[600-developer-smtp.md]. The EHLO command serves two purposes: it identifies the client to the server and requests a list of the ESMTP features supported by the server^[600-developer-smtp.md]. If the server's response includes support for TLS, the client can send the STARTTLS command to request a TLS handshake and negotiate a secure encryption layer^[600-developer-smtp.md].

  • [[SMTP]]
  • [[TLS]]

Sources

^[600-developer-smtp.md]