http://busylog.net/telnet-imap-commands-note/ Telnet IMAP Commands Note
https://www.cnblogs.com/qiubole/archive/2007/11/23/970180.html IMAP命令学习
http://www.faqs.org/rfcs/rfc3501.html RFC 3501 - INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1 英文
http://blog.csdn.net/qqnnhhbb/article/details/6428681 中文
原文：http://www.cnblogs.com/onelikeone/p/7865471.html