if err != nil {
					t.Fatalf("failed to parse certificate: %v", err)
				}

				tlsConnectionState = &tls.ConnectionState{
					PeerCertificates: []*x509.Certificate{serverCert},
				}
			}

			resp := &http.Response{
				TLS: tlsConnectionState,
			}

			if sanChecker.CheckPeerCertificates(resp.TLS.PeerCertificates) {
				sanChecker.IncreaseMetricsCounter(nil)
			}

	}
	c.conn = tls.Client(c.conn, config)
	c.Text = textproto.NewConn(c.conn)
	c.tls = true
	return c.ehlo()
}

// TLSConnectionState returns the client's TLS connection state.
// The return values are their zero values if [Client.StartTLS] did
// not succeed.
func (c *Client) TLSConnectionState() (state tls.ConnectionState, ok bool) {
	tc, ok := c.conn.(*tls.Conn)
	if !ok {
		return
	}

		testHookStartTLS(cfg) // set the RootCAs
		if err := c.StartTLS(cfg); err != nil {
			t.Errorf("StartTLS: %v", err)
			return
		}
		cs, ok := c.TLSConnectionState()
		if !ok {
			t.Errorf("TLSConnectionState returned ok == false; want true")
			return
		}
		if cs.Version == 0 || !cs.HandshakeComplete {
			t.Errorf("ConnectionState = %#v; expect non-zero Version and HandshakeComplete", cs)

pkg net/mail, method (*AddressParser) ParseList(string) ([]*Address, error)
pkg net/mail, type AddressParser struct
pkg net/mail, type AddressParser struct, WordDecoder *mime.WordDecoder
pkg net/smtp, method (*Client) TLSConnectionState() (tls.ConnectionState, bool)
pkg net/url, method (*URL) EscapedPath() string
pkg net/url, type URL struct, RawPath string
pkg os, func LookupEnv(string) (string, bool)
pkg os/signal, func Ignore(...os.Signal)

		{"(*Client).Noop", Method, 10},
		{"(*Client).Quit", Method, 0},
		{"(*Client).Rcpt", Method, 0},
		{"(*Client).Reset", Method, 0},
		{"(*Client).StartTLS", Method, 0},
		{"(*Client).TLSConnectionState", Method, 5},
		{"(*Client).Verify", Method, 0},
		{"Auth", Type, 0},
		{"CRAMMD5Auth", Func, 0},
		{"Client", Type, 0},
		{"Client.Text", Field, 0},
		{"Dial", Func, 0},
		{"NewClient", Func, 0},