| bufio | Package bufio implements buffered I/O. It wraps an io.Reader or io.Writer object, creating another object (Reader or Writer) that also implements the interface but provides buffering and some help for textual I/O. |
| flag | Package flag implements command-line flag parsing. |
| github.com/emersion/go-message/textproto | Package textproto implements low-level manipulation of MIME messages. |
| github.com/emersion/go-milter | Package milter provides an interface to implement milter mail filters |
| log | Package log implements a simple logging package. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| time | Package time provides functionality for measuring and displaying time. |