SmtpClient.EnableSsl Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Specify whether the SmtpClient uses Secure Sockets Layer (SSL) to encrypt the connection.
public:
property bool EnableSsl { bool get(); void set(bool value); };public bool EnableSsl { get; set; }member this.EnableSsl : bool with get, setPublic Property EnableSsl As BooleanProperty Value
true if the SmtpClient uses SSL; otherwise, false. The default is false.
Examples
The following code example establishes an SSL connection with the SMTP server and uses the connection to send an email.
public static void CreateTestMessage(string server)
{
string to = "jane@contoso.com";
string from = "ben@contoso.com";
MailMessage message = new MailMessage(from, to);
message.Subject = "Using the new SMTP client.";
message.Body = @"Using this new feature, you can send an email message from an application very easily.";
SmtpClient client = new SmtpClient(server);
// Credentials are necessary if the server requires the client
// to authenticate before it will send email on the client's behalf.
client.UseDefaultCredentials = true;
client.EnableSsl = true;
client.Send(message);
}
Remarks
The EnableSsl property specifies whether SSL is used to access the specified SMTP mail server.
The default value for this property can also be set in a machine or application configuration file. Any changes made to the EnableSsl property override the configuration file settings.
The SmtpClient class only supports the SMTP Service Extension for Secure SMTP over Transport Layer Security as defined in RFC 3207. In this mode, the SMTP session begins on an unencrypted channel, then a STARTTLS command is issued by the client to the server to switch to secure communication using SSL. See RFC 3207 published by the Internet Engineering Task Force (IETF) for more information.
An alternate connection method is where an SSL session is established up front before any protocol commands are sent. This connection method is sometimes called SMTP/SSL, SMTP over SSL, or SMTPS and by default uses port 465. This alternate connection method using SSL is not currently supported.
You can use ClientCertificates to specify which client certificates should be used to establish the SSL connection. The ServerCertificateValidationCallback allows you to reject the certificate provided by the SMTP server. The SecurityProtocol property allows you to specify the version of the SSL protocol to use.
Note
If the EnableSsl property is set to true, and the SMTP mail server does not advertise STARTTLS in the response to the EHLO command, then a call to the Send or SendAsync methods will throw an SmtpException.
