root@dex:~# apt-get install sendmailReading package lists... DoneBuilding dependency tree... DoneThe following extra packages will be installed: procmail rmail sendmail-base sendmail-bin sendmail-cf sensible-mdaSuggested packages: sendmail-doc logcheck sasl2-bin libsasl2-modules libsasl2-modules-plain libsasl2-digestmd5-plain libsasl2-digestmd5-des cyrus-commonRecommended packages: resolvconfThe following packages will be REMOVED: postfixThe following NEW packages will be installed: procmail rmail sendmail sendmail-base sendmail-bin sendmail-cf sensible-mda0 upgraded, 7 newly installed, 1 to remove and 0 not upgraded.Need to get 0B/2283kB of archives.After unpacking 2830kB of additional disk space will be used.Do you want to continue [Y/n]? Ydpkg: postfix: dependency problems, but removing anyway as you request: mailx depends on exim4 | mail-transport-agent; however: Package exim4 is not installed. Package mail-transport-agent is not installed. Package postfix which provides mail-transport-agent is to be removed.(Reading database ... 68733 files and directories currently installed.)Removing postfix ...invoke-rc.d: unknown initscript, /etc/init.d/postfix not found.dpkg: error processing postfix (--remove): subprocess pre-removal script returned error exit status 100Errors were encountered while processing: postfixE: Sub-process /usr/bin/dpkg returned an error code (1)root@dex:~#