| container/list | Package list implements a doubly linked list. |
| crypto/rand | Package rand implements a cryptographically secure random number generator. |
| encoding/binary | Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/emersion/go-message | Package message implements reading and writing multipurpose messages. |
| io | Package io provides basic interfaces to I/O primitives. |
| mime | Package mime implements parts of the MIME spec. |
| net/mail | Package mail implements parsing of mail messages. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| time | Package time provides functionality for measuring and displaying time. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |