126，163，sina，139都是行的。
hotmail ：imap_open("{pop.live.com:110/pop3}INBOX","xxx","xxx");
imap_errors() 输出：[0] => Connection failed to rds.live.com.nsatc.net,110: Connection timed out
"{imap.live.con:993/imap/ssl}INBOX"
imap_errors() 输出：[0] => Can't connect to nj.redirect.local,993: Connection timed out
qq ："{pop.qq.com:110/pop3}INBOX"
imap_errors() 输出：[0] => 454 POP????δ??????????????: http://service.mail.qq.com/cgi-bin/help?subtype=1&&id=28&&no=166 ACCOUNT IS NOT ENABLED FOR POP ACCESS. FOR MORE DETAILS PLEASE VISIT: http://service.mail.qq.com/cgi-bin/help?subtype=1&&id=28&&no=166
[1] => POP3 connection broken in response
"{imap.qq.com:993/imap/ssl}INBOX"
imap_errors() 输出：[0] => Can not authenticate to IMAP server:
sohu： "{pop.sohu.com:110/pop3}INBOX"
imap_errors() 输出：[0] => TLS/SSL failure for pop.sohu.com: SSL negotiation failed
"{imap.sohu.com:993/imap/ssl}INBOX"
imap_errors() 输出：[0] => TLS/SSL failure for imap.sohu.com: SSL negotiation failed
gmail ："{pop.gmail.com:110/pop3}INBOX"
imap_errors() 输出：[0] => Connection failed to gmail-pop.l.google.com,110: Connection timed out
[1] => Connection failed to gmail-pop.l.google.com,110: Connection timed out
"{imap.gmail.com:993/imap/ssl}INBOX"是可以收到的。
------解决方案--------------------
主要问题在于，了解每个邮件系统支持的功能，比如是否支持pop,是否支持ssl/tls,根据实际情况分别处理。推荐使用phpmailer，封装的不错
------解决方案--------------------
估计是人家邮件服务器的问题。不想让你这么玩