I still get that bloody error in a fresh install of Plesk 9.5.1
Apr 23 22:49:55 server1 before-remote[30085]: System error: Broken pipe
Apr 23 22:49:55 server1 before-remote[30085]: Unable to write data to stream
Apr 23 22:49:55 server1 before-remote[30085]: Some error occured
Apr 23 22:49:55 server1 postfix/spawn[30084]: warning: command /usr/lib/plesk-9.0/postfix-queue exit status 255
Centos OS 5
Apr 23 22:49:55 server1 before-remote[30085]: System error: Broken pipe
Apr 23 22:49:55 server1 before-remote[30085]: Unable to write data to stream
Apr 23 22:49:55 server1 before-remote[30085]: Some error occured
Apr 23 22:49:55 server1 postfix/spawn[30084]: warning: command /usr/lib/plesk-9.0/postfix-queue exit status 255
Centos OS 5