Implement SMTPS support

smtp.go

@@ -326,7 +326,27 @@ func SendMail(addr string, a smtp.Auth, from string, to []string, msg []byte) er
 			return err
 		}
 	}
-	c, err := Dial(addr)
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return err
+	}
+	var c *Client
+	if port == "465" || port == "smtps" {
+		config := &tls.Config{ServerName: host}
+		conn, err := tls.Dial("tcp", addr, config)
+		if err != nil {
+			return err
+		}
+		defer conn.Close()
+		c, err = NewClient(conn, host)
+		if err != nil {
+			return err
+		}
+		if err = c.hello(); err != nil {
+			return err
+		}
+	} else {
+		c, err = Dial(addr)
 		if err != nil {
 			return err
 		}
@@ -343,6 +363,7 @@ func SendMail(addr string, a smtp.Auth, from string, to []string, msg []byte) er
 				return err
 			}
 		}
+	}
 	if a != nil && c.ext != nil {
 		if _, ok := c.ext["AUTH"]; !ok {
 			return errors.New("smtp: server doesn't support AUTH")