* INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 [RFC 3501]: https://tools.ietf.org/html/rfc3501
    *  Collected Extensions to IMAP4 ABNF [RFC 4466]: https://tools.ietf.org/html/rfc4466
      * IMAP4 Multimailbox SEARCH Extension [RFC 7377]: https://tools.ietf.org/html/rfc7377
    * Internet Message Access Protocol (IMAP) CATENATE Extension [RFC 4469]: https://tools.ietf.org/html/rfc4469
      * The Internet Email to Support Diverse Service Environments (Lemonade) Profile [RFC 5550]: https://tools.ietf.org/html/rfc5550
    * IMAP Extensions: Quick Flag Changes Resynchronization (CONDSTORE) and Quick Mailbox Resynchronization (QRESYNC) [RFC 7162]: https://tools.ietf.org/html/rfc7162
    * WITHIN Search Extension to the IMAP Protocol [RFC 5032]: https://tools.ietf.org/html/rfc5032
    * IMAP Extension for Referencing the Last SEARCH Result [RFC 5182]: https://tools.ietf.org/html/rfc5182
    * IMAP Support for UTF-8 [RFC 6855]: https://tools.ietf.org/html/rfc6855
    * Use of SRV Records for Locating Email Submission/Access Services [RFC 6186]: https://tools.ietf.org/html/rfc6186
    * Simplified POP and IMAP Downgrading for Internationalized Email [RFC 6858]: https://tools.ietf.org/html/rfc6858
    * Updated Transport Layer Security (TLS) Server Identity Check Procedure for Email-Related Protocols [RFC 7817]: https://tools.ietf.org/html/rfc7817