On 24.2.2012, at 17.07, Wilberth Perez wrote: > My question was because constantly we received brute force attack from > some of ip address which uses pop3 service to affect dovecot's login > proccess. > > For example: > > dovecot: Error: pipe() failed: Too many open files > dovecot: Error: Temporary failure in creating login processes, slowing > down for now
This is your main problem. Increase ulimit -n so Dovecot won't stop creating login processes (or alternatively decrease the max number of login processes). Newer Dovecot versions warn at startup if the fd limit is too low.
