I created a virtual mail user for postfix virtual mailboxes with a gid/uid of 5555, but now every new user I create starts at > 5555, is it possible to reset the autonumbering so normal users will be back in the low 100s? I know this appears pedantic, but I am OCD AND 5555 is supposed to signify a "special" user, much like 65534 does for anonymous NFS user.
Confirming that ssgelm's solution works. I changed
/etc/login.defs and set the UID_MAX and GID_MAX to 5000, and all new users are now getting uids/gids in the low 500s (expected behavior).