fttUseRequireTLS

fttUseRequireTLS = 2

Example

function RequiresStartTLS(Mode: TvxTLSType): Boolean;
begin
  Result := Mode = fttUseRequireTLS;
end;

Usage

fttUseRequireTLS requires a successful explicit STARTTLS-style upgrade and fails when TLS is unavailable or negotiation fails.

Additional Technical Info

fttUseRequireTLS is ordinal 2 of TvxTLSType. It maps directly to Indy utUseRequireTLS. Like explicit mode, the client begins on the regular/explicit protocol port and performs the protocol upgrade.

This is the fail-closed explicit mode. Installed Indy raises when TLS capability is unavailable, the negotiation command fails or the handshake fails. Application authentication/data should proceed only after a successful encrypted upgrade.

Required TLS still does not by itself validate server identity, choose a safe protocol version or configure trust roots/client certificates. Combine it with the SSL client/certificate settings and use an endpoint/port that supports the correct STARTTLS-style command. Use implicit mode instead when the server expects TLS from connect.

The example only compares metadata and was source-reviewed; no STARTTLS, network, certificate, runtime or image test ran.

External references

• Indy TIdUseTLS source.

Created 2026-07-15