Thanks for the fast answer. > This mean this is an occasional error, not a permanent one ? > What do you do to solve this ? We get these messages last week only, before that we don't get this kind of messages in the logs. About our sent messages the people receive them when mail server is working, the messages are in the queue i suppose. I'm trying to understand what is the problem, i can't do anything at this moment. We get also these messages in the maillog: Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: non-LMTP response from hermod.iguanait.com[/var/lib/imap/socket/lmtp]:2aaaac385000-2aaaac386000 rw-p 00012000 fd:00 12452021 /lib64/libresolv-2.5.so Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: to prevent loss of mail, turn off command pipelining for /var/lib/imap/socket/lmtp with the lmtp_discard_lhlo_keyword_address_maps parameter Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: non-LMTP response from hermod.iguanait.com[/var/lib/imap/socket/lmtp]:2aaaac386000-2aaaac388000 rw-p 2aaaac386000 00:00 0 Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: to prevent loss of mail, turn off command pipelining for /var/lib/imap/socket/lmtp with the lmtp_discard_lhlo_keyword_address_maps parameter Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: non-LMTP response fromhermod.iguanait.com[/var/lib/imap/socket/lmtp]:2aaaac388000-2aaaac479000 r-xp 00000000 fd:00 12452057 /lib64/libdb-4.3.so Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: to prevent loss of mail, turn off command pipelining for /var/lib/imap/socket/lmtp with the lmtp_discard_lhlo_keyword_address_maps parameter Sep 12 12:57:49 hermod postfix/lmtp[14429]: warning: non-LMTP response from hermod.iguanait.com[/var/lib/imap/socket/lmtp]: 2aaaac67d000-2aaaac685000 r-xp 00000000 fd:00 6590877 /usr/lib64/libwrap.so.0.7.6 I increased only proccess limits to be 200. There we have running mysql only. Yes, the hardware is ok. We have 4 GB RAM, 8 GB Swap space, the machines are ok. I think that this is not related with bad RAM or something similar, because if there is some bad block memory, then probably we will receive this kind of messages from other applications too. What can i do in this situation? ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html