[Dovecot] localhost deliver(root@vlocalhost): setgid(5001) failed with euid=8, gid=8, egid=8: Operation not permitted

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}