关于SSH和接收邮件的问题

minibug

由于数次登陆失败，得到如下提示：

could not open terminal session channel
reson:the channel could not be open because the connection failed.
server error details:
the transport closed cleanly,but ther ewere still channels active.
all channels are being closed.

我重启了服务器，可是问题依旧，在接收email的时候如果数次输入密码错误，就无法登陆，请问：
1、如何清除失败的session
2、如何设置尝试登陆的次数