Install it setuid root as described here http://wiki.dovecot.org/LDA.
Alexander Gert Cuykens wrote: > How can i give lda dovecot permision to set user and goup id to 5001 > > dovecot unix - n n - - pipe > flags=DRhu user=mail:mail argv=/usr/lib/dovecot/deliver -f ${sender} > -d ${recipient}