有关更多信息，请参见https://blogs.msdn.microsoft.com/vikas/2008/04/29/bug-asp-net-2-0-passwordrecovery-web-control-cannot-send-emails-to-ssl-enabled-smtp-servers/。

对于.NET 4：可以。

见http://theoldsewingfactory.com/2011/01/06/enable-ssl-in-web-config-for-smtpclient/

<configuration>
    <system.net>
        <mailSettings>
            <smtp deliveryMethod=”network”>
                <network host="localhost"
                         port="25"
                         enableSsl="true"
                         defaultCredentials="true" />
            </smtp>
        </mailSettings>
    </system.net>
</configuration>