RSET

RSET is a command used in the Simple Mail Transfer Protocol (SMTP) to reset the current mail transaction without closing the network connection. It is defined in RFC 5321, the standard specification for SMTP, and has historically appeared in earlier RFCs as well. The command is client-initiated and is intended to abort a partially formed message so that a new mail transaction can begin.

When a client issues RSET, the server discards any envelope state associated with the current transaction. This includes the sender address (MAIL FROM), any recipient addresses (RCPT TO), and any data buffered during a DATA transmission. After processing RSET, the server returns to the initial, ready state for a new mail transaction. If no mail transaction is active, the command typically has no substantive effect beyond ensuring the connection remains open. The usual server response to a successful reset is 250 OK.

RSET is commonly used when an error is encountered during message composition or during command processing, allowing the client to start over without disconnecting. It is distinct from QUIT, which terminates the SMTP session, and from other state-changing commands like MAIL FROM or RCPT TO. While RSET clears the current envelope, some authentication or session-level state may be preserved or managed separately by the server according to its policy.

See also: SMTP command set (HELO/EHLO, MAIL FROM, RCPT TO, DATA, QUIT), RFC 5321, and related SMTP protocol documentation. Example client-server interaction: Client sends RSET; server replies with 250 OK.