解决ubuntu Email服务器imap连接超过最大限制方法。

1、打开Courier-IMAP配置文件（/etc/courier/imapd）：

#  cd /etc/courier/imapd

2、重新配置MAXDAEMONS和MAXPERIP数值

[...]

##NAME: MAXDAEMONS:0

#

#  Maximum number of IMAP servers started

#

MAXDAEMONS=40

##NAME: MAXPERIP:0

#

#  Maximum number of connections to accept from the same IP address

MAXPERIP=20

[...]

3、重启Courier-IMAP服务

# /etc/init.d/courier-imap restart

参考链接： https://www.howtoforge.com/courier-imap-imapd-maximum-connection-limit-reached-for#error-courierimap-imapd-maximum-connection-limit-reached-for