Specifies the security protocols that the SmtpClient class supports.
This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.
The SmtpClient class uses the SecurityProtocols enumeration to specify one or more security protocols to be used when establishing a connection with a remote host. Multiple protocols may be specified if necessary and the actual protocol used will be negotiated with the remote host. It is recommended that most applications use protocolDefault when creating a secure connection.
| Member Name | Description | Value |
|---|---|---|
| protocolNone | No security protocol will be used, a secure connection will not be established. | 0 |
| protocolSSL2 | The SSL 2.0 protocol has been selected. Note that this protocol has been deprecated and is no longer widely used. It is not recommended that this protocol be used when establishing secure connections. | 1 |
| protocolSSL3 | The SSL 3.0 protocol has been selected. This version of the protocol and the TLS protocol are the most commonly used security protocols. In most cases, this protocol is only selected if TLS is not supported by the remote host. | 2 |
| protocolTLS1 | The TLS 1.0, 1.1 or 1.2 protocol has been selected. The latest version of the protocol that is supported by both the client and server will be automatically selected. This protocol and SSL 3.0 are the most commonly used security protocols. | 8 |
| protocolSSL | Any version of the Secure Sockets Layer (SSL) protocol should be used. The actual protocol version used will be negotiated with the remote host. | 3 |
| protocolTLS | Any version of the the Transport Layer Security (TLS) protocol should be used. The actual protocol version used will be negotiated with the remote host. | 8 |
| protocolDefault | The default selection of security protocols will be used when establishing a connection. The TLS 1.2, 1.1, 1.0 and SSL 3.0 protocols will be negotiated with the host, in that order of preference. This option will always request the latest version of the available security protocols and is the recommended value. | 10 |
| protocolUnknown | An unknown or unsupported security protocol has been specified. This value indicates an error condition. | 4096 |
Namespace: SocketTools
Assembly: SocketTools.SmtpClient (in SocketTools.SmtpClient.dll)