README for dovecot 1.0.x REQUIREMENTS PRE-INSTALL Create a user/group dovecot with a unused id < 99: 'groupadd -g 26 dovecot' 'useradd -g dovecot -u 26 -d /var/run/dovecot -s /bin/false dovecot' 'passwd -l dovecot' POST-INSTALL PRECAUTION The configuration file has had a lot of changes between 0.99 and 1.0, so it's better to just modify the included dovecot.conf file manually than to update the existing one. See http://wiki.dovecot.org/moin.cgi/UpgradingDovecot