package mail-stack-delivery (not installed) failed to install/upgrade: subprocess installed post-removal script returned error exit status 1

 Ubuntu release 11.04

installed and tried to configure dovecot lastest version.

ProblemType: Package
DistroRelease: Ubuntu 11.04
Package: mail-stack-delivery (not installed)
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
AptOrdering:
 mail-stack-delivery: Purge
 mailutils: Purge
 postfix: Purge
Architecture: i386
Date: Thu Jun 23 08:51:41 2011
DpkgTerminalLog:
 Removing mail-stack-delivery ...
 postconf: fatal: open /etc/postfix/main.cf for reading: No such file or directory
 dpkg: error processing mail-stack-delivery (--purge):
  subprocess installed post-removal script returned error exit status 1
ErrorMessage: subprocess installed post-removal script returned error exit status 1
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release i386 (20110427.1)
SourcePackage: dovecot
Title: package mail-stack-delivery (not installed) failed to install/upgrade: subprocess installed post-removal script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)