[Dovecot] Configure unsuccessful login attempts

[Greg Pearson]

> You could use fail2ban, see also: http://wiki.dovecot.org/HowTo/Fail2Ban

So I guess the result would be to the login process become unresponsive, 
right? I am not sure this would be what I want. The desired behaviour 
for me would be to reject the connection even if the password becomes 
correct after several failures. I realise this would not help under DoS 
scenarios (in which I think fail2ban is targetting). I will give it a 
try, of course, but I was wondering if another approach is possible. 
Generally speaking, it would be really nice if Dovecot itself had such 
options.