Ok, think I found the cause... The server I try to install to has heartbeat/cluster software installed. I already has a group with GID 90: # grep 90 /etc/group haclient:x:90: The postfix rpm has hardcoded: /usr/sbin/groupadd -g 90 -r postdrop 2>/dev/null So that's the reason I get the messages... Thx for all your help Rainer Rainer Traut schrieb: > Thx for your answer. > > Ned Slider schrieb: >> Rainer Traut wrote: >>> Trying to switch from sendmail to postfix I did: >>> >>> # yum remove sendmail >>> >>> which resulted in erasing of: >>> mdadm sendmail-doc sendmail sendmail-cf mutt fetchmail redhat-lsb >>> >>> I did then: >>> >>> yum -y install redhat-lsb.x86_64 postfix >>> >>> and got this error: >>> >>> Installing: postfix ######################### >>> [1/2] >>> postfix: fatal: file /etc/postfix/main.cf: parameter setgid_group: >>> unknown group name: postdrop >>> warning: group postdrop does not exist - using root >>> warning: group postdrop does not exist - using root >>> warning: group postdrop does not exist - using root >>> warning: group postdrop does not exist - using root >>> Installing: redhat-lsb ######################### >>> [2/2] > >> You don't need to remove sendmail, you can just use system-switch-mail >> to set postfix as the MTA. >> > > I knew that thx. > I tested the exact same steps on our internal testmachine. Must admit it > has EL5.2 x86_64 on it but did not show this behaviour. >