hi all I've noticed that for sending big mails (10MB) it can take up to 30 min until they are sent. So I investigated a bit into the problem. I deactivated amavis and dkim, so they do not seem to be part of the problem. What happens is, that as soon as I write a bigger e-mail, the system load goes up from 0 to around 2.5 and when the mail is send, goes back to 0 again, but there is almost no cpu usage at all. So it should have something to do with the I/O system I guess. iotop tells me that cleanup is writing at around incredible 60 kb/s to the disk. All other processes work perfectly and don't get slowed down while the mail is send, I can even copy to the same partition at normal speed. It is just cleanup which seems to be so slow. There is also still enough memory left. Besides the speed, email delivery works perfectly, there are also no log messages indicating anything. I don't think it has to do with the network card since I also tried out
smtp-source -t crap@localhost -l 102400000 127.0.0.1 and it shows the exact same behaviour. Anybody has any idea what the problem might be? I'm using postfix 2.11.3-1 on a debian jessie (stable) with kernel 4.9.0-0-686-pae. thanks in advance michael
