pkg net/smtp, type ServerInfo struct, TLS bool
pkg net/textproto, func CanonicalMIMEHeaderKey(string) string
pkg net/textproto, func Dial(string, string) (*Conn, error)
pkg net/textproto, func NewConn(io.ReadWriteCloser) *Conn
pkg net/textproto, func NewReader(*bufio.Reader) *Reader
pkg net/textproto, func NewWriter(*bufio.Writer) *Writer
pkg net/textproto, method (*Conn) Close() error