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. Rainer