Specifies the options 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 SmtpOptions enumeration to specify one or more options to be used when establishing a connection with a remote host. Multiple options may be specified if necessary.
| Member Name | Description | Value |
|---|---|---|
| optionNone | No option specified. | 0 |
| optionDefault | The default connection option. This is the same as specifying optionExtended. | 1 |
| optionExtended | Extended SMTP commands should be used if possible. This option enables features such as authentication and delivery status notification. If this option is not specified, the class will not attempt to use any extended features. | 1 |
| optionTunnel | This option specifies that a tunneled TCP connection and/or port-forwarding is being used to establish the connection to the server. This changes the behavior of the client with regards to internal checks of the destination IP address and remote port number, default feature selection and how the connection is established. This option also forces all connections to be outbound and enables the firewall compatibility features in the client. | 1024 |
| optionTrustedSite | This option specifies that the server is trusted. The server certificate will not be validated and the connection will always be permitted. This option only affects connections using either the SSL or TLS protocols. | 2048 |
| optionSecure | This option specifies that the client should attempt to establish a secure connection with the server. The server must support secure connections using either the SSL or TLS protocol. | 4096 |
| optionExplicitSSL | This option specifies that the client should attempt to establish a secure explicit SSL session. The initial connection to the server is not encrypted, and the client will attempt to negotiate a secure connection by sending the STARTTLS command to the server. Some servers may require this option when connecting to the server on ports other than the default secure port of 465. | 4096 |
| optionImplicitSSL | This option specifies that the client should attempt to establish a secure implicit SSL session. The SSL handshake is initiated immediately after the connection to the server has been established. | 8192 |
| optionFreeThread | This option specifies that class methods may be called from any thread, and not only the thread that established the connection. Using this option disables certain internal safety checks that are made by the class and may result in unexpected behavior unless you ensure that access to the class instance is synchronized across multiple threads. | 524288 |
Namespace: SocketTools
Assembly: SocketTools.SmtpClient (in SocketTools.SmtpClient.dll)