[CentOS] postfix install error: fatal file /etc/postfix/main.cf: parameter setgid_group: unknown group name: postdrop

Tue Aug 26 14:36:32 UTC 2008
Ned Slider <ned at unixmail.co.uk>

Rainer Traut wrote:
> Hi,
> 
> sys: Centos 5.2 x86_64
> 
> 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]
> 
> I checked and indeed there is no group postdrop on the system.
> On an El5 system I see the group.
> 
> Thx
> Rainer
> 


You don't need to remove sendmail, you can just use system-switch-mail 
to set postfix as the MTA.

There is documentation on setting up a basic postfix server (on CentOS 
5) on the Wiki here:

http://wiki.centos.org/HowTos/postfix